=head1 NAME

Mail::IMAPClient - An IMAP Client API

=head1 SYNOPSIS

  use Mail::IMAPClient;

  my $imap = Mail::IMAPClient->new(
    Server   => 'localhost',
    User     => 'username',
    Password => 'password',
    Ssl      => 1,
    Uid      => 1,
  );

  my $folders = $imap->folders
    or die "List folders error: ", $imap->LastError, "\n";
  print "Folders: @$folders\n";

  $imap->select( $Opt{folder} )
    or die "Select '$Opt{folder}' error: ", $imap->LastError, "\n";

  $imap->fetch_hash("FLAGS", "INTERNALDATE", "RFC822.SIZE")
    or die "Fetch hash '$Opt{folder}' error: ", $imap->LastError, "\n";

  $imap->logout
    or die "Logout error: ", $imap->LastError, "\n";

=head1 DESCRIPTION

This module provides methods implementing the IMAP protocol to support
interacting with IMAP message stores.

The module is used by constructing or instantiating a new IMAPClient
object via the L</new> constructor method.  Once the object has been
instantiated, the L</connect> method is either implicitly or
explicitly called.  At that point methods are available that implement
the IMAP client commands as specified in B<RFC3501>.  When processing
is complete, the L</logout> object method should be called.

This documentation is not meant to be a replacement for RFC3501 nor
any other IMAP related RFCs.

Note that this documentation uses the term I<folder> in place of
RFC3501's use of I<mailbox>.  This documentation reserves the use of
the term I<mailbox> to refer to the set of folders owned by a specific
IMAP id.

=head2 Connection State

RFC3501 defines four possible states for an IMAP connection: not
authenticated, authenticated, selected, and logged out.  These
correspond to the IMAPClient constants C<Connected>, C<Authenticated>,
C<Selected>, and C<Unconnected>, respectively.  These constants can be
used in conjunction with the L</Status> method to determine the status
of an IMAPClient object and its underlying IMAP session.

Note that an IMAPClient object can be in the C<Unconnected> state both
before a server connection is made and after it has ended.  This
differs slightly from RFC3501, which does not define a pre-connection
status.  For a discussion of the methods available for examining the
IMAPClient object's status, see the section labeled
L</"Status Methods">, below.

=head2 Advanced Authentication Mechanisms

RFC3501 defines two commands for authenticating to an IMAP server:

=over 4

=item LOGIN

LOGIN is for plain text authentication.

=item AUTHENTICATE

AUTHENTICATE for more advanced and/or secure authentication mechanisms.

=back

Mail::IMAPClient supports the following AUTHENTICATE mechanisms:

=over 4

=item DIGEST-MD5

DIGEST-MD5 authentication requires the L<Authen::SASL> and
L<Digest::MD5> modules.  See also L</Authuser>.

=item CRAM-MD5

CRAM-MD5 requires the L<Digest::HMAC_MD5> module.

=item PLAIN (SASL)

PLAIN (SASL) authentication allows the optional use of the L</Proxy>
parameter.  RFC 4616 documents this syntax for SASL PLAIN:

  message = [authzid] UTF8NUL authcid UTF8NUL passwd

When L</Proxy> is defined, L</User> is used as 'authzid' and L</Proxy>
is used as 'authcid'.  Otherwise, L</User> is used as 'authcid'.

=item NTLM

NTLM authentication requires the L<Authen::NTLM> module.  See also
L</Domain>.

=back

=head2 Errors

If you attempt an operation that results in an error, then you can
retrieve the text of the error message by using the L</LastError>
method.  However, the L</LastError> method is an object method (not a
class method) and can only be used once an object is successfully
created.  In cases where an object is not successfully created the
C<$@> variable is set with an error message.

Mail::IMAPClient resets C<$@> and L</LastError> to undef before most
IMAP requests, so the values only have a short lifespan.
L</LastError> will always contain error info from the last error,
until another error is encountered, another IMAP command is issued or
it is explicitly cleared.

Please note that the use of C<$@> is subject to change in the future
release so it is best to use L</LastError> for error checking once a
Mail::IMAPClient object has been created.

Errors in the L</new> method can prevent your object from ever being
created.  If the L</Server>, L</User>, and L</Password> parameters are
supplied to L</new>, it will attempt to call L</connect> and
L</login>.  Any of these methods could fail and cause the L</new>
method call to return C<undef> and leaving the variable C<$@> is set
to an error message.

WARNING: (due to historical API behavior) on errors, many methods may
return undef regardless of LIST/SCALAR context.  Therefore, it may be
wise to use most methods in a scalar context.  Regardless, check
L</LastError> for details on errors.

=head2 Transactions

RFC3501 requires that each line in an IMAP conversation be prefixed
with a tag.  A typical conversation consists of the client issuing a
tag-prefixed command string, and the server replying with one of more
lines of output.  Those lines of output will include a command
completion status code prefixed by the same tag as the original
command string.

The IMAPClient module uses a simple counter to ensure that each client
command is issued with a unique tag value.  This tag value is referred
to by the IMAPClient module as the transaction number.  A history is
maintained by the IMAPClient object documenting each transaction.  The
L</Transaction> method returns the number of the last transaction, and
can be used to retrieve lines of text from the object's history.

The L</Clear> parameter is used to control the size of the session
history so that long-running sessions do not eat up unreasonable
amounts of memory.  See the discussion of L</Clear> parameter for more
information.

The L</Report> transaction returns the history of the entire IMAP
session since the initial connection or for the last L</Clear>
transactions.  This provides a record of the entire conversation,
including client command strings and server responses, and is a
wonderful debugging tool as well as a useful source of raw data for
custom parsing.

=head1 CLASS METHODS

There are a couple of methods that can be invoked as class methods.
Generally they can be invoked as an object method as well.  Note that
if the L</new> method is called as an object method, the object
returned is identical to what have would been returned if L</new> had
been called as a class method.  It doesn't give you a copy of the
original object.

=head2 new

Example:

  my $imap = Mail::IMAPClient->new(%args)
    or die "new failed: $@\n";

The L</new> method creates a new instance of an IMAPClient object.

If the L</Server> parameter is passed as an argument to B<new>, then
B<new> will implicitly call the L</connect> method, placing the new
object in the I<Connected> state.  If L</User> and L</Password> values
are also provided, then L</connect> will in turn call L</login>, and
the resulting object will be returned from B<new> in the
I<Authenticated> state.

If the L</Server> parameter is not supplied then the IMAPClient
object is created in the I<Unconnected> state.

If the B<new> method is passed arguments then those arguments will be
treated as a list of key=>value pairs.  The key should be one of the
parameters as documented under L</"Parameters"> below.

Here are some examples:

  use Mail::IMAPClient;
  
  # returns an unconnected Mail::IMAPClient object:
  my $imap = Mail::IMAPClient->new;
  # ...
  # intervening code using the 1st object, then:
  # (returns a new, authenticated Mail::IMAPClient object)
  $imap = Mail::IMAPClient->new(
      Server   => $host,
      User     => $id,
      Password => $pass,
      Clear    => 5,   # Unnecessary since '5' is the default
      # ...            # Other key=>value pairs go here
  )
    or die "Cannot connect to $host as $id: $@";

See also L</Parameters>, L</connect> and L</login> for more
information on how to manually connect and login after B<new>.

=head2 Quote

Example:

  $imap->search( HEADER => 'Message-id' => \$imap->Quote($msg_id) );

The B<Quote> method accepts a value as an argument and returns its
argument as a correctly quoted string or a literal string.  Since
version 3.17 Mail::IMAPClient automatically quotes search arguments we
use a SCALARREF so search will not modify or re-quote the value
returned by B<Quote>.

Note this method should not be used on folder names for
Mail::IMAPClient methods, since methods that accept folder names as an
argument will quote the folder name arguments automatically.

If you are getting unexpected results when running methods with values
that have (or might have) embedded spaces, double quotes, braces, or
parentheses, then calling B<Quote> may be necessary.  This method
should B<not> be used with arguments that are wrapped in quotes or
parens if those quotes or parens are required by RFC3501.  For
example, if the RFC requires an argument in this format:

  ( argument )

and the argument is (or might be) "pennies (from heaven)", then one
could use:

  $argument = "(" . $imap->Quote($argument) . ")"

Of course, the fact that sometimes these characters are sometimes
required delimiters is precisely the reason you must quote them when
they are I<not> delimiting.

However, there are times when a method fails unexpectedly and may
require the use of B<Quote> to work.  Should this happen, you can
probably file a bug/enhancement request for Mail::IMAPClient to
safeguard the particular call/case better.

An example is RFC822 Message-id's, which I<usually> don't contain
quotes or parens.  When dealing with these it is usually best to take
proactive, defensive measures from the very start and use B<Quote>.

=head2 Range

Example:

  my $parsed = $imap->parse_headers(
      $imap->Range( $imap->messages ), "Date", "Subject"
  );

The B<Range> method will condense a list of message sequence numbers
or message UID's into the most compact format supported by RFC3501.
It accepts one or more arguments, each of which can be:

=over 4

=item a) a message number,

=item b) a comma-separated list of message numbers,

=item c) a colon-separated range of message numbers (i.e. "$begin:$end")

=item d) a combination of messages and message ranges, separated by commas
(i.e. 1,3,5:8,10), or

=item e) a reference to an array whose elements are like I<a)> through I<d)>.

=back

The B<Range> method returns a L<Mail::IMAPClient::MessageSet> object.
The object uses L<overload> and if treated as a string it will act
like a string.  This means you can ignore its objectivity and just
treat it like a string whose value is your message set expressed in
compact format.

This method provides an easy way to add or remove messages from a
message set.

For more information see L<Mail::IMAPClient::MessageSet>.

=head2 Rfc3501_date

Example:

  $Rfc3501_date = $imap->Rfc3501_date($seconds);
  # or:
  $Rfc3501_date = Mail::IMAPClient->Rfc3501_date($seconds);

The B<Rfc3501_date> method accepts one input argument, a number of
seconds since the epoch date.  It returns an RFC3501 compliant date
string for that date (as required in date-related arguments to SEARCH,
such as "since", "before", etc.).

=head2 Rfc3501_datetime

Example:

  $date = $imap->Rfc3501_datetime($seconds);
  # or:
  $date = Mail::IMAPClient->Rfc3501_datetime($seconds);

The B<Rfc3501_datetime> method accepts one or two arguments: a
obligatory timestamp and an optional zone.  The zone shall be
formatted as C<< [+-]\d{4} >>, and defaults to C<< +0000 >>.  The
timestamp follows the definition of the output of the platforms
specific C<time>, usually in seconds since Jan 1st 1970.  However, you
have to correct the number yourself for the zone.

=head2 Rfc822_date

Example:

  $Rfc822_date = $imap->Rfc822_date($seconds);
  # or:
  $Rfc822_date = Mail::IMAPClient->Rfc822_date($seconds);

The B<Rfc822_date> method accepts one input argument, a number of
seconds since the epoch date.  It returns an RFC822 compliant date
string for that date (without the 'Date:' prefix).  Useful for putting
dates in message strings before calling L</append>, L</search>, etc.

=head2 Strip_cr

Examples:

  my $stripped = $imap->Strip_cr($string);
  # or:
  my @list = $imap->some_imap_method;
  @list = $imap->Strip_cr(@list);
  # or:
  my $list = [ $imap->some_imap_method ];   # returns an array ref
  $list = $imap->Strip_cr($list);

The B<Strip_cr> method strips carriage returns from input and returns
the new string to the caller.  This method accepts one or more lines
of text as arguments, and returns those lines with all <CR><LF>
sequences changed to <LF>.  Any input argument with no carriage
returns is returned unchanged.  If the first argument (not counting
the class name or object reference) is an array reference, then
members of that array are processed as above and subsequent arguments
are ignored.  If the method is called in scalar context then an array
reference is returned instead of an array of results.

NOTE: B<Strip_cr> does not remove new line characters.

=head1 OBJECT METHODS

Object methods must be invoked against objects created via the L</new>
method and cannot be invoked as class methods.

There object methods typically fall into one of two categories.  There
are mailbox methods which participate in the IMAP session's
conversation (i.e. they issue IMAP client commands) and object control
methods which do not result in IMAP commands but which may affect
later commands or provide details of previous ones.

This object control methods can be further broken  down into two
types, Parameter accessor methods, which affect the behavior of future
mailbox methods, and L</"Status Methods">, which report on the affects
of previous mailbox methods.

Methods that do not result in new IMAP client commands being issued
(such as the L</Transaction>, L</Status>, and L</History> methods) all
begin with an uppercase letter, to distinguish them from methods that
do correspond to IMAP client commands.  Class methods and eponymous
parameter methods likewise begin with an uppercase letter because they
also do not correspond to an IMAP client command.

As a general rule, mailbox control methods return C<undef> on failure
and something besides C<undef> when they succeed.  This rule is
modified in the case of methods that return search results.  When
called in a list context, searches that do not find matching results
return an empty list.  When called in a scalar context, searches with
no hits return 'undef' instead of an array reference.  If you want to
know why you received no hits, you should check L</LastError> or
C<$@>, which will be empty if the search was successful but had no
matching results but populated with an error message if the search
encountered a problem (such as invalid parameters).

A number of IMAP commands do not have corresponding Mail::IMAPClient
methods.  Patches are welcome.  In the pre-2.99 releases of this
module, they were automatically created (AUTOLOAD), but that was very
error-prone and stalled the progress of this module.

=head1 Mailbox Control Methods

=head2 append

Example:

  my $uid_or_true = $imap->append( $folder, $msgtext )
    or die "Could not append: ", $imap->LastError;

WARNING: This method may be deprecated in the future, consider using
L</append_string> instead of this method.

The B<append> method adds a message to the specified folder.  See
L</append_string> for details as it is effectively an alias for that
method.

DEPRECATED BEHAVIOR: Additional arguments are added to the message
text, separated with <CR><LF>.

=head2 append_string

Example:

   # brackets indicate optional arguments (not array refs):
   my $uidort = $imap->append_string( $folder, $msgtext [,$flags [,$date ] ] )
       or die "Could not append_string: ", $imap->LastError;

Arguments:

=over 4

=item $folder

the name of the folder to append the message to

=item $msgtext

the message text (including headers) of the message

=item $flags

An optional list of flags to set.  The list must be specified as
a space-separated list of flags, including any backslashes that may be
necessary and optionally enclosed by parenthesis.

=item $date

An optional RFC3501 date argument to set as the internal date.  It
should be in the format described for I<date_time> fields in RFC3501,
i.e. "dd-Mon-yyyy hh:mm:ss +0000".

If you want to specify a date/time but you don't want any flags then
specify I<undef> as the third ($flags) argument.

=back

Returns:

=over 4

=item error: undef

On error, undef can be returned regardless of LIST/SCALAR context.
Check L</LastError> for details.

=item success: UID or $imap

With UIDPLUS the UID of the new message is returned otherwise a true
value (currently $self) is returned.

=back

To protect against "bare newlines", B<append> will insert a carriage
return before any newline that is "bare".

=head2 append_file

Example:

  my $new_msg_uid = $imap->append_file(
      $folder,
      $file,
      [ undef, $flags, $date ] # optional
  ) or die "Could not append_file: ", $imap->LastError;

The B<append_file> method adds a message to the specified folder.
Note: The brackets in the example indicate optional arguments; they do
not mean that the argument should be an array reference.

Arguments:

=over 4

=item $folder

the name of the folder to append the message to

=item $file

a filename, filehandle or SCALAR reference which holds an
RFC822-formatted message

=item undef

a deprecated argument used as a place holder for backwards
compatibility

=item $flags

The optional argument is handled the same as append_string.

=item $date

The optional argument is handled the same as append_string (RFC3501
date), with the exception that if $date is "1" (one) then the
modification time (mtime) of the file will be used.

=back

Returns:

=over 4

=item error: undef

On error, undef can be returned regardless of LIST/SCALAR context.
Check L</LastError> for details.

=item success: UID or $imap

With UIDPLUS the UID of the new message is returned otherwise a true
value (currently $self) is returned.

=back

To protect against "bare newlines", B<append_file> will insert a
carriage return before any newline that is "bare".

The B<append_file> method provides a mechanism for allowing large
messages to be appended without holding the whole file in memory.

Version note: In 2.x an optional third argument to use for
C<input_record_separator> was allowed, however this argument is
ignored/not supported as of 3.x.

=head2 authenticate

Example:

  $imap->authenticate( $authentication_mechanism, $coderef )
    or die "Could not authenticate: ", $imap->LastError;

This method implements the AUTHENTICATE IMAP client command.  It can
be called directly or may be called by L</login> if the
L</Authmechanism> parameter is set to anything except 'LOGIN'.

The B<authenticate> method accepts two arguments, an authentication
type to be used (ie CRAM-MD5) and a code or subroutine reference to
execute to obtain a response.  The B<authenticate> method assumes that
the authentication type specified in the first argument follows a
challenge-response flow.  The B<authenticate> method issues the IMAP
Client AUTHENTICATE command and receives a challenge from the server.
That challenge (minus any tag prefix or enclosing '+' characters but
still in the original base64 encoding) is passed as the only argument
to the code or subroutine referenced in the second argument.  The
return value from the 2nd argument's code is written to the server as
is, except that a <CR><LF> sequence is appended if necessary.

If one or both of the arguments are not specified in the call to
B<authenticate> but their corresponding parameters have been set
(L</Authmechanism> and L</Authcallback>, respectively) then the parameter
values are used. Arguments provided to the method call however will
override parameter settings.

If you do not specify a second argument and you have not set the
L</Authcallback> parameter, then the first argument must be
one of the authentication mechanisms for which Mail::IMAPClient
has built in support.

See also the L</login> method, which is the simplest form of
authentication defined by RFC3501.

=head2 before

Example:

  my @msgs = $imap->before($Rfc3501_date)
    or warn "No messages found before $Rfc3501_date.\n";

The B<before> method works just like the L</"since"> method, below,
except it returns a list of messages whose internal system dates are
before the date supplied as the argument to the B<before> method.

=head2 body_string

Example:

  my $string = $imap->body_string($msgId)
    or die "Could not body_string: ", $imap->LastError;

The B<body_string> method accepts a message sequence number (or a
message UID, if the L</Uid> parameter is set to true) as an argument
and returns the message body as a string.  The returned value contains
the entire message in one scalar variable, without the message
headers.

=head2 bodypart_string

Example:

  my $string = $imap->bodypart_string(
      $msgid, $part_number, $length, $offset
  ) or die "Could not get bodypart string: ", $imap->LastError;

The B<bodypart_string> method accepts a message sequence number (or a
message UID, if the L</Uid> parameter is set to true) and a body part
as arguments and returns the message part as a string.  The returned
value contains the entire message part (or, optionally, a portion of
the part) in one scalar variable.

If an optional third argument is provided, that argument is the number
of bytes to fetch.  (The default is the whole message part.)  If an
optional fourth argument is provided then that fourth argument is the
offset into the part at which the fetch should begin.  The default is
offset zero, or the beginning of the message part.

If you specify an offset without specifying a length then the offset
will be ignored and the entire part will be returned.

B<bodypart_string> will return C<undef> if it encounters an error.

=head2 capability

Example:

  my $features = $imap->capability
    or die "Could not determine capability: ", $imap->LastError;

The B<capability> method returns an array of capabilities as returned
by the CAPABILITY IMAP Client command, or a reference to an array of
capabilities if called in scalar context.  If the CAPABILITY IMAP
Client command fails for any reason then the B<capability> method will
return C<undef>.  Supported capabilities are cached by the client,
however, this cache is deleted after a connection is set to
I<Authenticated> and when L</starttls> is called.

See also L</has_capability>.

=head2 close

Example:

  $imap->close or die "Could not close: $@\n";

The B<close> method is used to close the currently selected folder via
the CLOSE IMAP client command.  According to RFC3501, the CLOSE
command performs an implicit EXPUNGE, which means that any messages
that are flagged as I<\Deleted> (i.e. with the L</delete_message>
method) will now be deleted.  If you haven't deleted any messages then
B<close> can be thought of as an "unselect".

Note: this closes the currently selected folder, not the IMAP session.

See also L</delete_message>, L</expunge>, and RFC3501.

=head2 compress

Example:

  $imap->compress or die "Could not enable RFC4978 compression: $@\n";

The B<compress> method accepts no arguments.  This method is used to
instruct the server to use the DEFLATE (RFC1951) compression
extension.  See the L</Compress> attribute for how to specify
arguments for use during the initialization process.

Version note: method added in Mail::IMAPClient 3.30

=head2 connect

Example:

  $imap->connect or die "Could not connect: $@\n";

The B<connect> method connects an imap object to the server.  It
returns C<undef> if it fails to connect for any reason.  If values are
available for the L</User> and L</Password> parameters at the time
that B<connect> is invoked, then B<connect> will call the L</login>
method after connecting and return the result of the L</login> method
to B<connect>'s caller.  If either or both of the L</User> and
L</Password> parameters are unavailable but the connection to the
server succeeds then B<connect> returns a pointer to the IMAPClient
object.

The L</Server> parameter must be set (either during L</new> method
invocation or via the L</Server> object method) before invoking
B<connect>.  When the parameter is an absolute file path, an UNIX
socket will get opened.  If the L</Server> parameter is supplied to
the L</new> method then B<connect> is implicitly called during object
construction.

The B<connect> method sets the state of the object to C<Connected> if
it successfully connects to the server.  It returns C<undef> on
failure.

=head2 copy

Example:

  # Here brackets indicate optional arguments:
  my $uidList = $imap->copy($folder, $msg_1 [ , ... , $msg_n ])
    or die "Could not copy: $@\n";

Or:

  # Now brackets indicate an array ref!
  my $uidList = $imap->copy($folder, [ $msg_1, ... , $msg_n ])
    or die "Could not copy: $@\n";

The B<copy> method requires a folder name as the first argument, and a
list of one or more messages sequence numbers (or messages UID's, if
the I<UID> parameter is set to a true value).  The message sequence
numbers or UID's should refer to messages in the currently selected
folder.  Those messages will be copied into the folder named in the
first argument.

The B<copy> method returns C<undef> on failure and a true value if
successful.  If the server to which the current Mail::IMAPClient
object is connected supports the UIDPLUS capability then the true
value returned by B<copy> will be a comma separated list of UID's,
which are the UID's of the newly copied messages in the target folder.

=head2 create

Example:

  $imap->create($new_folder)
    or die "Could not create $new_folder: $@\n";

The B<create> method accepts one argument, the name of a folder (or
what RFC3501 calls a "mailbox") to create.  If you specify additional
arguments to the B<create> method and your server allows additional
arguments to the CREATE IMAP client command then the extra argument(s)
will be passed to your server.

If you specify additional arguments to the B<create> method and your
server does not allow additional arguments to the CREATE IMAP client
command then the extra argument(s) will still be passed to your server
and the create will fail.

B<create> returns a true value on success and C<undef> on failure.

=head2 date

Example:

  my $date = $imap->date($msg);

The B<date> method accepts one argument, a message sequence number (or
a message UID if the L</Uid> parameter is set to a true value).  It
returns the date of message as specified in the message's RFC822
"Date: " header, without the "Date: " prefix.

The B<date> method is a short-cut for:

  my $date = $imap->get_header($msg,"Date");

=head2 delete

Example:

  $imap->delete($folder) or die "Could not delete $folder: $@\n";

The B<delete> method accepts a single argument, the name of a folder
to delete.  It returns a true value on success and C<undef> on
failure.

=head2 deleteacl

Example:

  $imap->deleteacl( $folder, $userid )
    or die "Could not delete acl: $@\n";

The B<deleteacl> method accepts two input arguments, a folder name, a
user id (or authentication identifier, to use the terminology of
RFC2086).  See RFC2086 for more information.  (This is somewhat
experimental and its implementation may change.)

=head2 delete_message

Example:

  my @msgs = $imap->seen;
  scalar(@msgs) and $imap->delete_message(\@msgs)
    or die "Could not delete_message: $@\n";

The above could also be rewritten like this:

  # scalar context returns array ref
  my $msgs = scalar($imap->seen);

  scalar(@$msgs) and $imap->delete_message($msgs)
    or die "Could not delete_message: $@\n";

Or, as a one-liner:

  $imap->delete_message( scalar($imap->seen) )
    or warn "Could not delete_message: $@\n";
  # just give warning in case failure is
  # due to having no 'seen' msgs in the 1st place!

The B<delete_message> method accepts a list of arguments.  If the
L</Uid> parameter is not set to a true value, then each item in the
list should be either:

=over 4

=item *

a message sequence number,

=item *

a comma-separated list of message sequence numbers,

=item *

a reference to an array of message sequence numbers, or

=back

If the L</Uid> parameter is set to a true value, then each item in the
list should be either:

=over 4

=item *

a message UID,

=item *

a comma-separated list of UID's, or

=item *

a reference to an array of message UID's.

=back

The messages identified by the sequence numbers or UID's will be
deleted.  If successful, B<delete_message> returns the number of
messages it was told to delete.  However, since the delete is done by
issuing the I<+FLAGS.SILENT> option of the STORE IMAP client command,
there is no guarantee that the delete was successful for every
message.  In this manner the B<delete_message> method sacrifices
accuracy for speed.  Generally, though, if a single message in a list
of messages fails to be deleted it's because it was already deleted,
which is what you wanted anyway so why worry about it? If there is a
more severe error, i.e. the server replies "NO", "BAD", or, banish the
thought, "BYE", then B<delete_message> will return C<undef>.

If you must have guaranteed results then use the IMAP STORE client
command (via the default method) and use the +FLAGS (\Deleted) option,
and then parse your results manually.

Eg:

  $imap->store( $msg_id, '+FLAGS (\Deleted)' );
  my @results = $imap->History( $imap->Transaction );
    ...           # code to parse output goes here

(Frankly I see no reason to bother with any of that; if a message
doesn't get deleted it's almost always because it's already not there,
which is what you want anyway.  But 'your mileage may vary' and all
that.)

The IMAPClient object must be in C<Selected> status to use the
B<delete_message> method.

B<NOTE>: All the messages identified in the input argument(s) must be in
the currently selected folder.  Failure to comply with this
requirement will almost certainly result in the wrong message(s) being
deleted.

B<ADDITIONAL NOTE>: In the grand tradition of the IMAP protocol,
deleting a message doesn't actually delete the message.  Really.  If
you want to make sure the message has been deleted, you need to
expunge the folder (via the L</expunge> method, which is implemented
via the default method).  Or at least L</close> it.  This is generally
considered a feature, since after deleting a message, you can change
your mind and undelete it at any time before your L</expunge> or
L</close>.

See also: the L</delete> method, to delete a folder, the L</expunge>
method, to expunge a folder, the L</restore_message> method to
undelete a message, and the L</close> method (implemented here via the
default method) to close a folder.  Oh, and don't forget about RFC3501.

=head2 deny_seeing

Example:

  # Reset all read msgs to unread
  # (produces error if there are no seen msgs):
  $imap->deny_seeing( scalar($imap->seen) )
    or die "Could not deny_seeing: $@\n";

The B<deny_seeing> method accepts a list of one or more message
sequence numbers, or a single reference to an array of one or more
message sequence numbers, as its argument(s).  It then unsets the
"\Seen" flag for those messages (so that you can "deny" that you ever
saw them).  Of course, if the L</Uid> parameter is set to a true value
then those message sequence numbers should be unique message id's.

Note that specifying C<$imap-E<gt>deny_seeing(@msgs)> is just a
shortcut for specifying C<$imap-E<gt>unset_flag("Seen",@msgs)>.

=head2 disconnect

Example:

  $imap->disconnect or warn "Could not logout: $@\n";

This method calls L</logout>, see L</logout> for details.

=head2 done

Example:

  my $tag = $imap->idle or warn "idle failed: $@\n";
  doSomethingA();
  my $idlemsgs = $imap->idle_data() or warn "idle_data error: $@\n";
  doSomethingB();
  my $results = $imap->done($tag) or warn "Error from done: $@\n";

The B<done> method tells the IMAP server to terminate the IDLE
command.  The only argument is the I<tag> (identifier) received from
the previous call to L</idle>.  If I<tag> is not specified a default
I<tag> based on the B<Count> attribute is assumed to be the I<tag> to
look for in the response from the server.

If an invalid I<tag> is specified, or the default I<tag> is wrong,
then B<done> will hang indefinitely or until a timeout occurs.

If B<done> is called when an L</idle> command is not active then the
server will likely respond with an error like I<* BAD Invalid tag>.

On failure <undef> is returned and L</LastError> is set.

See also L</idle>, L</idle_data> and L</Results>.

=head2 examine

Example:

  $imap->examine($folder) or die "Could not examine: $@\n";

The B<examine> method selects a folder in read-only mode and changes
the object's state to "Selected".  The folder selected via the
B<examine> method can be examined but no changes can be made unless it
is first selected via the L</select> method.

The B<examine> method accepts one argument, which is the name of the
folder to select.

=head2 exists

Example:

  $imap->exists($folder) or warn "$folder not found: $@\n";

Accepts one argument, a folder name.  Returns true if the folder
exists or false if it does not exist.

=head2 expunge

Example:

  $imap->expunge($folder) or die "Could not expunge: $@\n";

The B<expunge> method accepts one optional argument, a folder name.
It expunges the folder specified as the argument, or the currently
selected folder (if any) when no argument is supplied.

Although RFC3501 does not permit optional arguments (like a folder
name) to the EXPUNGE client command, the L</expunge> method does.
Note: expunging a folder deletes the messages that have the \Deleted
flag set (i.e. messages flagged via L</delete_message>).

See also the L</close> method, which "deselects" as well as expunges.

=head2 fetch

Usage:

  $imap->fetch( [$seq_set|ALL], @msg_data_items )

Example:

  my $output = $imap->fetch(@args) or die "Could not fetch: $@\n";

The B<fetch> method implements the FETCH IMAP client command.  It
accepts a list of arguments, which will be converted into a
space-delimited list of arguments to the FETCH IMAP client command.
If no arguments are supplied then B<fetch> does a FETCH ALL.  If the
L</Uid> parameter is set to a true value then the first argument will
be treated as a UID or list of UID's, which means that the UID FETCH
IMAP client command will be run instead of FETCH.  (It would really be
a good idea at this point to review RFC3501.)

If called in array context, B<fetch> will return an array of output
lines.  The output lines will be returned just as they were received
from the server, so your script will have to be prepared to parse out
the bits you want.  The only exception to this is literal strings,
which will be inserted into the output line at the point at which they
were encountered (without the {nnn} literal field indicator).  See
RFC3501 for a description of literal fields.

If B<fetch> is called in a scalar context, then a reference to an array
(as described above) is returned instead of the entire array.

B<fetch> returns C<undef> on failure.  Inspect L</LastError> or C<$@>
for an explanation of your error.

=head2 fetch_hash

Usage:

  $imap->fetch_hash( [$seq_set|ALL], @msg_data_items, [\%msg_by_ids] )

Examples:

  my $hashref = $imap->fetch_hash("RFC822.SIZE");

 OR

  my $hashref = {};
  $imap->fetch_hash( "RFC822.SIZE", $hashref );
  print "Msg #$_ is $hashref->{$_}->{'RFC822.SIZE'} bytes\n" for (keys %$hashref);

The B<fetch_hash> method accepts a list of message attributes to be
fetched (as described in RFC3501).  It returns a hash whose keys are
all the messages in the currently selected folder and whose values are
key-value pairs of fetch keywords and the message's value for that
keyword (see sample output below).

If B<fetch_hash> is called in scalar context, it returns a reference
to the hash instead of the hash itself.  If the last argument is a hash
reference, then that hash reference will be used as the place where
results are stored (and that reference will be returned upon
successful completion).  If the last argument is not a reference then
it will be treated as one of the FETCH attributes and a new hash will
be created and returned (either by value or by reference, depending on
the context in which B<fetch_hash> was called).

For example, if you have a folder with 3 messages and want the size
and internal date for each of them, you could do the following:

  use Mail::IMAPClient;
  use Data::Dumper;
  # ... other code goes here
  $imap->select($folder);
  my $hash = $imap->fetch_hash( "RFC822.SIZE", "INTERNALDATE" );
  # (Same as:
  #  my $hash = $imap->fetch_hash("RFC822.SIZE");
  #  $imap->fetch_hash( "INTERNALDATE", $hash );
  # ).
  print Data::Dumper->Dumpxs( [$hash], ['$hash'] );

This would result in L<Data::Dumper> output similar to the following:

   $hash = {
       '1' => {
                  'INTERNALDATE' => '21-Sep-2002 18:21:56 +0000',
                  'RFC822.SIZE' => '1586',
              },
       '2' => {
                  'INTERNALDATE' => '22-Sep-2002 11:29:42 +0000',
                  'RFC822.SIZE' => '1945',
              },
       '3' => {
                  'INTERNALDATE' => '23-Sep-2002 09:16:51 +0000',
                  'RFC822.SIZE' => '134314',
              }
     };

By itself this method may be useful for tasks like obtaining the size
of every message in a folder.  It issues one command and receives one
(possibly long!) response from the server.

If the fetch request causes the server to return data in a
parenthesized list, the data within the parenthesized list may be
escaped via the Escape() method. Use the Unescape() method to get the
raw values back in this case.

=head2 flags

Example:

  my @flags = $imap->flags($msgid)
    or die "Could not flags: $@\n";

The B<flags> method implements the FETCH IMAP client command to list a
single message's flags.  It accepts one argument, a message sequence
number (or a message UID, if the L</Uid> parameter is true), and
returns an array (or a reference to an array, if called in scalar
context) listing the flags that have been set.  Flag names are
provided with leading backslashes.

As of version 1.11, you can supply either a list of message id's or a
reference to an array of message id's (which means either sequence
number, if the Uid parameter is false, or message UID's, if the Uid
parameter is true) instead of supplying a single message sequence
number or UID.  If you do, then the return value will not be an array
or array reference; instead, it will be a hash reference, with each
key being a message sequence number (or UID) and each value being a
reference to an array of flags set for that message.

For example, if you want to display the flags for every message in the
folder where you store e-mail related to your plans for world
domination, you could do something like this:

  use Mail::IMAPClient;
  my $imap = Mail::IMAPClient->new(
      Server   => $imaphost,
      User     => $login,
      Password => $pass,
      Uid      => 1,        # optional
  );

  $imap->select("World Domination");
  # get the flags for every message in my 'World Domination' folder
  $flaghash = $imap->flags( scalar( $imap->search("ALL") ) );

  # pump through sorted hash keys to print results:
  for my $k ( sort { $flaghash->{$a} <=> $flaghash->{$b} } keys %$flaghash ) {
      # print: Message 1: \Flag1, \Flag2, \Flag3
      print "Message $k:\t", join( ", ", @{$flaghash->{$k}} ), "\n";
  }

=head2 folders

Example:

  $imap->folders or die "Could not list folders: $@\n";

The B<folders> method returns an array listing the available folders.
It will only be successful if the object is in the I<Authenticated> or
I<Selected> states.

The B<folders> method accepts one optional argument, which is a
prefix.  If a prefix is supplied to the B<folders> method, then only
folders beginning with the prefix will be returned.

For example:

  print join( ", ", $imap->folders ), ".\n";
  # Prints:
  # INBOX, Sent, Projects, Projects/Completed, Projects/Ongoing, Projects Software.
  print join( ", ", $imap->folders("Projects") ), ".\n";
  # Prints:
  # Projects, Projects/Completed, Projects/Ongoing, Projects Software.
  print join( ", ", $imap->folders("Projects" . $imap->separator) ), ".\n";
  # Prints:
  # Projects/Completed, Projects/Ongoing

Please note that documentation previously suggested that if you just
want to list a folder's subfolders (and not the folder itself), then
you need to include the hierarchy separator character (as returned by
the L</separator> method). However, this does not match the behavior
of the existing implementation, so you will need to manually exclude
the parent folder from the results.

=head2 folders_hash

  my @fhashes = $imap->folders_hash
    or die "Could not get list of folder hashes.\n";

The B<folders_hash> method accepts one optional argument, which is a
prefix.  If a prefix is supplied to the B<folders_hash> method, then
only folders beginning with the prefix will be returned.

An array(ref) of hashes is returned that contain information about the
requested folders.  Each hash contains three keys (name, attrs, delim)
and looks like the following:

  {
    name  => 'Mail/Box/Name',
    attrs => [ '\Marked', '\HasNoChildren' ],
    delim => '/',
  }

IMAP servers implementing RFC6154 return attributes to be used to
identify special-use mailboxes (folders).

  my $sattr_re = /\A\\(?:All|Archive|Drafts|Flagged|Junk|Sent|Trash)\Z/;
  foreach my $fhash (@fhashes) {
      next unless defined $fhash->{name};
      my @special = grep { $sattr_re } @{ $fhash->{attrs} };
      print("special: $fhash->{name} : @special\n") if (@special);
  }

Version note: method added in Mail::IMAPClient 3.34

=head2 xlist_folders (DEPRECATED)

This method is deprecated as of version 3.34.  Please use folders_hash
instead.  See RFC6154 for attributes to be used to identify
special-use mailboxes (folders).

Example:

  my $xlist = $imap->xlist_folders
    or die "Could not get xlist folders.\n";

IMAP servers implementing the XLIST extension (such as Gmail)
designate particular folders to be used for particular functions.
This is useful in the case where you want to know which folder should
be used for Trash when the actual folder name can't be predicted
(e.g. in the case of Gmail, the folder names change depending on the
user's locale settings).

The B<xlist_folders> method returns a hash listing any "xlist" folder
names, with the values listing the actual folders that should be used
for those names.  For example, using this method with a Gmail user
using the English (US) locale might give this output from
L<Data::Dumper>:

  $VAR1 = {
      'Inbox'   => 'Inbox',
      'AllMail' => '[Gmail]/All Mail',
      'Trash'   => '[Gmail]/Trash',
      'Drafts'  => '[Gmail]/Drafts',
      'Sent'    => '[Gmail]/Sent Mail',
      'Spam'    => '[Gmail]/Spam',
      'Starred' => '[Gmail]/Starred'
  };

The same list for a user using the French locale might look like this:

  $VAR1 = {
      'Inbox'   => 'Bo&AO4-te de r&AOk-ception',
      'AllMail' => '[Gmail]/Tous les messages',
      'Trash'   => '[Gmail]/Corbeille',
      'Drafts'  => '[Gmail]/Brouillons',
      'Sent'    => '[Gmail]/Messages envoy&AOk-s',
      'Spam'    => '[Gmail]/Spam',
      'Starred' => '[Gmail]/Suivis'
  };

Mail::IMAPClient recognizes the following "xlist" folder names:

=over 4

=item Inbox

=item AllMail

=item Trash

=item Drafts

=item Sent

=item Spam

=item Starred

=back

These are currently the only ones supported by Gmail.  The XLIST
extension is not documented, and there are no other known
implementations other than Gmail, so this list is based on what Gmail
provides.

If the server does not support the XLIST extension, this method
returns undef.

Version note: method added in Mail::IMAPClient 3.21

=head2 has_capability

Example:

  my $has_feature = $imap->has_capability($feature)
    or die "Could not do has_capability($feature): $@\n";

Returns true if the IMAP server to which the IMAPClient object is
connected has the capability specified as an argument to
B<has_capability>.  If the server does not have the capability then
the empty string "" is returned, if the underlying L</capability>
calls fails then undef is returned.

=head2 idle

Example:

  my $tag = $imap->idle or warn "idle failed: $@\n";
  doSomethingA();
  my $idlemsgs = $imap->idle_data() or warn "idle_data error: $@\n";
  doSomethingB();
  my $results = $imap->done($tag) or warn "Error from done: $@\n";

The B<idle> method tells the IMAP server the client is ready to accept
unsolicited mailbox update messages (on the selected folder/mailbox).
This method is only valid on servers that support the IMAP IDLE
extension, see RFC2177 for details.

The B<idle> method accepts no arguments and returns the I<tag>
(identifier) that was sent by the client for this command.  This tag
should be supplied as the argument to L</done> when ending the IDLE
command.

On failure <undef> is returned and L</LastError> is set.

The method L</idle_data> may be used once B<idle> has been successful.
However, no mailbox operations may be called until the B<idle> command
has been terminated by calling L</done>.  Failure to do so will result
in an error and the idle command will typically be terminated by the
server.

See also L</idle_data> and L</done>.

=head2 idle_data

Usage:

  # an optional timeout in seconds may be specified
  $imap->idle_data( [$timeout] )

Example:

  my $tag = $imap->idle or warn "idle failed: $@\n";
  doSomethingA();
  my $idlemsgs = $imap->idle_data() or warn "idle_data error: $@\n";
  doSomethingB();
  my $results = $imap->done($tag) or warn "Error from done: $@\n";

The B<idle_data> method can be used to accept any unsolicited mailbox
update messages that have been sent by the server during an L</idle>
command.  This method does not send any commands to the server, it
simply looks for and optionally waits for data from the server and
returns that data to the caller.

The B<idle_data> method accepts an optional $timeout argument and
returns an array (or an array reference if called in scalar context)
with the messages from the server.

By default a timeout of 0 seconds is used (do not block).  Internally
the timeout is passed to L<perlfunc/select>.  The timeout controls how
long the select call blocks if there are no messages waiting to be
read from the server.

On failure <undef> is returned and L</LastError> is set.

See also L</imap> and L</done>.

Version note: method added in Mail::IMAPClient 3.23
Warning: this method is considered experimental and the
interface/output may change in a future version.

=head2 imap4rev1

Example:

  $imap->imap4rev1 or die "Could not imap4rev1: $@\n";

Returns true if the IMAP server to which the IMAPClient object is
connected has the IMAP4REV1 capability.  If the server does not have
the capability then the empty string "" is returned, if the underlying
L</capability> calls fails then undef is returned.

=head2 internaldate

Example:

  my $msg_internal_date = $imap->internaldate($msgid)
    or die "Could not internaldate: $@\n";

B<internaldate> accepts one argument, a message id (or UID if the
L</Uid> parameter is true), and returns that message's internal date
or undef if the call fails or internal date is not returned.

=head2 get_bodystructure

Example:

  my $bodyStructObject = $imap->get_bodystructure($msgid)
    or die "Could not get_bodystructure: $@\n";

The B<get_bodystructure> method accepts one argument, a message
sequence number or, if L</Uid> is true, a message UID.  It obtains the
message's body structure and returns a parsed
L<Mail::IMAPClient::BodyStructure> object for the message.

=head2 get_envelope

Example:

  my $envObject = $imap->get_envelope(@args)
    or die "Could not get_envelope: $@\n";

The B<get_envelope> method accepts one argument, a message sequence
number or, if L</Uid> is true, a message UID.  It obtains the
message's envelope and returns a
B<Mail::IMAPClient::BodyStructure::Envelope> object for the envelope,
which is just a version of the envelope that's been parsed into a Perl
object.

For more information on how to use this object once you've gotten it,
see the L<Mail::IMAPClient::BodyStructure> documentation.  (As of this
writing there is no separate pod document for
B<Mail::IMAPClient::BodyStructure::Envelope>.)

=head2 getacl

Example:

  my $hash = $imap->getacl($folder)
    or die "Could not getacl for $folder: $@\n";

B<getacl> accepts one argument, the name of a folder.  If no argument
is provided then the currently selected folder is used as the default.
It returns a reference to a hash.  The keys of the hash are userids
that have access to the folder, and the value of each element are the
permissions for that user.  The permissions are listed in a string in
the order returned from the server with no white space or punctuation
between them.

=head2 get_header

Example:

  my $messageId = $imap->get_header( $msg, "Message-Id" );

The B<get_header> method accepts two arguments, a message sequence
number or UID and the name of an RFC822 header (without the trailing
colon).  It returns the value for that header in the message whose
sequence number or UID was passed as the first argument.  If no value
can be found it returns C<undef>; if multiple values are found it
returns the first one.  Its return value is always a scalar.
B<get_header> uses case insensitive matching to get the value, so you
do not have to worry about the case of your second argument.

The B<get_header> method is a short-cut for:

  my $messageId = $imap->parse_headers($msg,"Subject")->{"Subject"}[0];

=head2 getquotaroot

Example:

  my $results = $imap->getquotaroot($mailboxname)
    or die "Could not getquotaroot for $mailboxname: $@\n";

The B<getquotaroot> method implements the RFC2087 GETQUOTAROOT
command.  The "$mailboxname" defaults to "INBOX" if no argument is
provided.

On error C<undef> is returned, otherwise L</Results> are returned.
The results should have the untagged QUOTAROOT response from the
server along with the QUOTAROOT's resource usage and limits in an
untagged QUOTA response.

See also B<RFC2087>, L</getquota>, L</setquota>, L</quota> and L</quota_usage>.

=head2 getquota

Example:

  my $results = $imap->getquota($quotaroot)
    or die "Could not getquota for $quotaroot: $@\n";

The B<getquota> method implements the RFC2087 GETQUOTA command.  The
"$quotaroot" defaults to "user/I<User>" if no argument is provided.

On error C<undef> is returned, otherwise L</Results> are returned.
The results from the server should have the untagged QUOTA response
from the server.

See also B<RFC2087>, L</getquotaroot>, L</quota> and L</quota_usage>.

=head2 quota

Example:

  my $limit = $imap->quota($quotaroot)
    or die "Could not get quota limit for $quotaroot: $@\n";

The B<quota> method takes the L</Results> from L<getquota> and parses
out the "STORAGE" limit returned by the server.  The "$quotaroot"
defaults to "INBOX" if no argument is provided.

On error C<undef> is returned, otherwise the integer "STORAGE" limit
provided by the server is returned.

See also B<RFC2087>, L</getquotaroot>, L</getquota> and L</quota_usage>.

=head2 quota_usage

Example:

  my $usage = $imap->quota_usage($quotaroot)
    or die "Could not get quota usage for $quotaroot: $@\n";

The B<quota_usage> method takes the L</Results> from L<getquota> and
parses out the "STORAGE" usage returned by the server.  The
"$quotaroot" defaults to "INBOX" if no argument is provided.

On error C<undef> is returned, otherwise the integer "STORAGE" usage
provided by the server is returned.

See also B<RFC2087>, L</getquotaroot>, L</getquota> and L</quota>.

=head2 setquota

Example:

  my $results = $imap->setquota( $quotaroot, $resource, $limit )
    or die "Could not setquota for $quotaroot: $@\n";

The B<setquota> method implements the RFC2087 SETQUOTA command.  It
accepts multiple pairs of $resource and $limit arguments.  The
"$quotaroot" defaults to "user/I<User>" if not defined.

On error C<undef> is returned, otherwise L</Results> are returned.

See also B<RFC2087>, L</getquotaroot> and L</getquota>.

=head2 is_parent

Example:

  my $hasKids = $imap->is_parent($folder);

The B<is_parent> method accepts one argument, the name of a folder. It
returns a value that indicates whether or not the folder has children.
The value it returns is either:

=over 4

=item C<1> (or a positive integer)

The C<\HasChildren> attribute is set, indicating that the folder has
children.

=item C<0> (zero)

The C<\HasNoChildren> attribute is set, indicating that the folder has
no children at this time.

=item C<undef>

The C<\NoInferiors> attribute is set, indicating the folder is not
permitted to have children.

=back

Eg:

  my $parenthood = $imap->is_parent($folder);
  if ( defined($parenthood) ) {
      if ($parenthood) {
          print "$folder has children.\n";
      }
      else {
          print "$folder is permitted children, but has none.\n";
      }
  }
  else {
      print "$folder is not permitted to have children.\n";
  }

=head2 list

Example:

  my @raw_output = $imap->list(@args)
    or die "Could not list: $@\n";

The B<list> method implements the IMAP LIST client command.  Arguments
are passed to the IMAP server as received, separated from each other
by spaces.  If no arguments are supplied then the default list command
C<tag LIST "" '*'> is issued.

The B<list> method returns an array (or an array reference, if called
in a scalar context).  The array is the unadulterated output of the
LIST command.  (If you want your output adulterated then see the
L</folders> method, above.)

An C<undef> value is returned in case of errors.  Be sure to check for
it.

=head2 listrights

Example:

  $imap->listrights( $folder, $user )
    or die "Could not listrights: $@\n";

The B<listrights> method implements the IMAP LISTRIGHTS client command
(L<RFC2086>).  It accepts two arguments, the foldername and a user id.
It returns the rights the specified user has for the specified folder.
If called in a scalar context then the rights are returned a strings,
with no punctuation or white space or any nonsense like that.  If called
in array context then B<listrights> returns an array in which each
element is one right.

=head2 login

Example:

  $imap->login or die "Could not login: $@\n";

The B<login> method implements the IMAP LOGIN client command to log
into the server.  It automatically calls L</authenticate> if the
I<Authmechanism> parameter is set to anything except 'LOGIN' otherwise
a clear text LOGIN is attempted.

The I<User> and I<Password> parameters must be set before the B<login>
method can be invoked.  On success, a Mail::IMAPClient object with the
Status of I<Authenticated> is returned.  On failure, undef is returned
and $@ is set.  The methods L</new>, L</connect>, and L</Socket> may
automatically invoke B<login> see the documentation of each method for
details.

If the L</Compress> parameter is set, the L</compress> method will
automatically be called after successful authentication.

See also L</proxyauth> and L</Proxy> for additional information
regarding ways of authenticating with a server via SASL and/or
PROXYAUTH.

=head2 proxyauth

Example:

  $imap->login( "admin", "password" );
  $imap->proxyauth("someuser");

The B<proxyauth> method implements the IMAP PROXYAUTH client command.
The command is used by Sun/iPlanet/Netscape IMAP servers to allow an
administrative user to masquerade as another user.

=head2 logout

Example:

  $imap->logout or die "Could not logout: $@\n";

The B<logout> method implements the LOGOUT IMAP client command.  This
method causes the server to end the connection and the IMAPClient
client enters the I<Unconnected> state.  This method does not, destroy
the IMAPClient object, thus the L</connect> and L</login> methods can
be used to establish a new IMAP session.

Note that RFC2683 section 3.1.2 (Severed connections) makes some
recommendations on how IMAP clients should behave.  It is up to the
user of this module to decide on the preferred behavior and code
accordingly.

Version note: documentation (from 2.x through 3.23) claimed that
Mail::IMAPClient would attempt to log out of the server during
B<DESTROY> if the object is in the L</Connected> state.  This
documentation was apparently incorrect from at least 2.2.2 and
possibly earlier versions on up.

=head2 lsub

Example:

  $imap->lsub(@args) or die "Could not lsub: $@\n";

The B<lsub> method implements the IMAP LSUB client command.  Arguments
are passed to the IMAP server as received, separated from each other
by spaces.  If no arguments are supplied then the default lsub command
C<tag LSUB "" '*'> is issued.

The B<lsub> method returns an array (or an array reference, if called
in a scalar context).  The array is the unaltered output of the LSUB
command.  If you want an array of subscribed folders then see the
L</subscribed> method, below.

=head2 mark

Example:

  $imap->mark(@msgs) or die "Could not mark: $@\n";

The B<mark> method accepts a list of one or more messages sequence
numbers, or a single reference to an array of one or more message
sequence numbers, as its argument(s).  It then sets the "\Flagged"
flag for those message(s).  Of course, if the L</Uid> parameter is set
to a true value then those message sequence numbers had better be
unique message id's.

Note that specifying C<$imap-E<gt>see(@msgs)> is just a shortcut for
specifying C<$imap-E<gt>set_flag("Flagged",@msgs)>.

=head2 Massage

Example:

  $imap->search(HEADER => 'Message-id' => $imap->Massage($msg_id,1));

WARNING: This method may be deprecated in the future, consider using
L</Quote> instead of this method.

The B<Massage> method accepts a value as an argument and, optionally,
a second value that, when true, indicates that the first argument is
not the name of an existing folder.

WARNING: If the first argument has double quotes at the beginning and
end of its value, those double quote will be stripped unless the
second argument does not evaluate to true.

It returns its argument as a correctly quoted string or a literal
string.

Note that you should rarely use this on folder names, since methods
that accept folder names as an argument will call B<Quote> for
you.

=head2 message_count

Example:

  my $msgcount = $imap->message_count($folder);
  defined($msgcount) or die "Could not message_count: $@\n";

The B<message_count> method accepts the name of a folder as an
argument and returns the number of messages in that folder.
Internally, it invokes the L</status> method (see above) and parses
out the results to obtain the number of messages.  If you don't supply
an argument to B<message_count> then it will return the number of
messages in the currently selected folder (assuming of course that
you've used the L</select> or L</examine> method to select it instead
of trying something funky).  Note that RFC2683 contains warnings about
the use of the IMAP I<STATUS> command (and thus the L</status> method
and therefore the B<message_count> method) against the currently
selected folder.  You should carefully consider this before using
B<message_count> on the currently selected folder.  You may be better
off using L</search> or one of its variants (especially L</messages>),
and then counting the results.  On the other hand, I regularly violate
this rule on my server without suffering any dire consequences.  Your
mileage may vary.

=head2 message_string

Example:

  my $string = $imap->message_string($msgid)
    or die "Could not message_string: $@\n";

The B<message_string> method accepts a message sequence number (or
message UID if L</Uid> is true) as an argument and returns the message
as a string.  The returned value contains the entire message in one
scalar variable, including the message headers.  Note that using this
method will set the message's "\Seen" flag as a side effect, unless
I<Peek> is set to a true value.

=head2 message_to_file

Example:

  $imap->message_to_file( $file, @msgs )
    or die "Could not message_to_file: $@\n";

The B<message_to_file> method accepts a filename or file handle and
one or more message sequence numbers (or message UIDs if L</Uid> is
true) as arguments and places the message string(s) (including RFC822
headers) into the file named in the first argument (or prints them to
the file handle, if a file handle is passed).  The returned value is
true on success and C<undef> on failure.

If the first argument is a reference, it is assumed to be an open
file handle and will not be closed when the method completes, If it is
a file, it is opened in append mode, written to, then closed.

Note that using this method will set the message's "\Seen" flag as a
side effect.  But you can use the L</deny_seeing> method to set it
back, or set the L</Peek> parameter to a true value to prevent setting
the "\Seen" flag at all.

This method currently works by making some basic assumptions about the
server's behavior, notably that the message text will be returned as a
literal string but that nothing else will be.  If you have a better
idea then I'd like to hear it.

=head2 message_uid

Example:

  my $msg_uid = $imap->message_uid($msg_seq_no)
    or die "Could not get uid for $msg_seq_no: $@\n";

The B<message_uid> method accepts a message sequence number (or
message UID if L</Uid> is true) as an argument and returns the
message's UID.  Yes, if L</Uid> is true then it will use the IMAP UID
FETCH UID client command to obtain and return the very same argument
you supplied.  This is an IMAP feature so don't complain to me about
it.

=head2 messages

Example:

  # Get a list of messages in the current folder:
  my @msgs = $imap->messages or die "Could not messages: $@\n";
  # Get a reference to an array of messages in the current folder:
  my $msgs = $imap->messages or die "Could not messages: $@\n";

If called in list context, the B<messages> method returns a list of
all the messages in the currently selected folder.  If called in
scalar context, it returns a reference to an array containing all the
messages in the folder.  If you have the L</Uid> parameter turned off,
then this is the same as specifying C<1 ... $imap-E<gt>L<message_count>>;
if you have UID set to true then this is the same as specifying
C<$imap-E<gt>L</search>("ALL")>.

=head2 migrate

Example:

  $imap_src->migrate( $imap_dest, "ALL", $targetFolder )
    or die "Could not migrate: ", $imap_src->LastError;

The B<migrate> method copies the indicated message(s) B<from> the
currently selected folder B<to> another Mail::IMAPClient object's
session.  It requires these arguments:

=over 4

=item 1.

a reference to the target Mail::IMAPClient object (not the calling
object, which is connected to the source account);

=item 2.

the message(s) to be copied, specified as either a) the message
sequence number (or message UID if the UID parameter is true) of a
single message, b) a reference to an array of message sequence numbers
(or message UID's if the UID parameter is true) or c) the special
string "ALL", which is a shortcut for the results of
C<L</search>("ALL")>.

=item 3.

the name of the destination folder on the target mailbox to receive
the message(s).  If this argument is not supplied or is I<undef> then
the currently selected folder on the calling object will be used. The
destination folder will be automatically created if necessary.

=back

The target ($imap_dest) Mail::IMAPClient object must not be the same
object as the source ($imap_src).

This method does not attempt to minimize memory usage.  In the future
it could be enhanced to (optionally) write message data to a temporary
file to avoid storing the entire message in memory.

To work around potential network timeouts on large messages, consider
setting L</Reconnectretry> to 1 on both $imap_src and $imap_dest.

See also C<Supportedflags>.

=head2 move

Example:

  my $newUid = $imap->move( $newFolder, $oldUid )
    or die "Could not move: $@\n";
  $imap->expunge;

The B<move> method moves messages from the currently selected folder
to the folder specified in the first argument to B<move>.  If the
L</Uid> parameter is not true, then the rest of the arguments should
be either:

=over 4

=item a)

a message sequence number,

=item b)

a comma-separated list of message sequence numbers, or

=item c)

a reference to an array of message sequence numbers.

=back

If the L</Uid> parameter is true, then the arguments should be:

=over 4

=item a)

a message UID,

=item b)

a comma-separated list of message UID's, or

=item c)

a reference to an array of message UID's.

=back

If the target folder does not exist then it will be created.

If move is successful, then it returns a true value.  Furthermore, if
the Mail::IMAPClient object is connected to a server that has the
UIDPLUS capability, then the true value will be the comma-separated
list of UID's for the newly copied messages.  The list will be in the
order in which the messages were moved which should correspond to the
order of the message UID provided by the caller.

If the move is not successful then B<move> returns C<undef>.

Note that a move really just involves copying the message to the new
folder and then setting the I<\Deleted> flag.  To actually delete the
original message you will need to run L</expunge> (or L</close>).

=head2 namespace

Example:

  my $refs = $imap->namespace
    or die "Could not namespace: $@\n";

The namespace method runs the NAMESPACE IMAP command (as defined in
RFC 2342).  When called in a list context, it returns a list of three
references.  Each reference looks like this:

  [
    [ $prefix_1, $separator_1 ],
    [ $prefix_2, $separator_2 ],
    [ $prefix_n, $separator_n ],
  ]

The first reference provides a list of prefixes and separator
characters for the available personal namespaces.  The second
reference provides a list of prefixes and separator characters for the
available shared namespaces.  The third reference provides a list of
prefixes and separator characters for the available public namespaces.

If any of the three namespaces are unavailable on the current server
then an 'undef' is returned instead of a reference.  So for example if
shared folders were not supported on the server but personal and
public namespaces were both available (with one namespace each), the
returned value might resemble this:

  [ [ "", "/" ] , undef, [ "#news", "." ] ];

If the B<namespace> method is called in scalar context, it returns a
reference to the above-mentioned list of three references, thus
creating a single structure that would pretty-print something like
this:

  $VAR1 = [
      [
          [ $user_prefix_1, $user_separator_1 ],
          [ $user_prefix_2, $user_separator_2 ],
          [ $user_prefix_n, $user_separator_n ],
      ],                    # or undef
      [
          [ $shared_prefix_1, $shared_separator_1 ],
          [ $shared_prefix_2, $shared_separator_2 ],
          [ $shared_prefix_n, $shared_separator_n ],
      ],                    # or undef
      [
          [ $public_prefix_1, $public_separator_1 ],
          [ $public_prefix_2, $public_separator_2 ],
          [ $public_prefix_n, $public_separator_n ],
      ],                    # or undef
  ];

=head2 on

Example:

  my @msgs = $imap->on($Rfc3501_date)
    or warn "Could not find messages sent on $Rfc3501_date: $@\n";

The B<on> method works just like the L</since> method, below, except
it returns a list of messages whose internal system dates are the same
as the date supplied as the argument.

=head2 parse_headers

Example:

  my $hashref = $imap->parse_headers($msg||\@msgs, "Date", "Subject")
    or die "Could not parse_headers: $@\n";

The B<parse_headers> method accepts as arguments a message sequence
number and a list of header fields.  It returns a hash reference in
which the keys are the header field names (without the colon) and the
values are references to arrays of values.  A picture would look
something like this:

  $hashref = $imap->parse_headers(1,"Date","Received","Subject","To");
  $hashref = {
      "Date"     => [ "Thu, 09 Sep 1999 09:49:04 -0400" ]  ,
      "Received" => [ q/
        from mailhub ([111.11.111.111]) by mailhost.bigco.com
        (Netscape Messaging Server 3.6)  with ESMTP id AAA527D for
        <bigshot@bigco.com>; Fri, 18 Jun 1999 16:29:07 +0000
        /, q/
        from directory-daemon by mailhub.bigco.com (PMDF V5.2-31 #38473)
        id <0FDJ0010174HF7@mailhub.bigco.com> for bigshot@bigco.com
        (ORCPT rfc822;big.shot@bigco.com); Fri, 18 Jun 1999 16:29:05 +0000 (GMT)
        /, q/
        from someplace ([999.9.99.99]) by smtp-relay.bigco.com (PMDF V5.2-31 #38473)
        with ESMTP id <0FDJ0000P74H0W@smtp-relay.bigco.com> for big.shot@bigco.com; Fri,
        18 Jun 1999 16:29:05 +0000 (GMT)
        /] ,
      "Subject" => [ qw/ Help! I've fallen and I can't get up!/ ] ,
      "To"      => [ "Big Shot <big.shot@bigco.com> ] ,
  };

The text in the example for the "Received" array has been formatted to
make reading the example easier.  The actual values returned are just
strings of words separated by spaces and with newlines and carriage
returns stripped off.  The I<Received> header is probably the main
reason that the B<parse_headers> method creates a hash of lists rather
than a hash of values.

If the second argument to B<parse_headers> is 'ALL' or if it is
unspecified then all available headers are included in the returned
hash of lists.

If you're not emotionally prepared to deal with a hash of lists then
you can always call the L</fetch> method yourself with the appropriate
parameters and parse the data out any way you want to.  Also, in the
case of headers whose contents are also reflected in the envelope, you
can use the L</get_envelope> method as an alternative to
L</parse_headers>.

If the L</Uid> parameter is true then the first argument will be
treated as a message UID.  If the first argument is a reference to an
array of message sequence numbers (or UID's if L</Uid> is true), then
B<parse_headers> will be run against each message in the array.  In
this case the return value is a hash, in which the key is the message
sequence number (or UID) and the value is a reference to a hash as
described above.

An example of using B<parse_headers> to print the date and subject of
every message in your smut folder could look like this:

  use Mail::IMAPClient;
  my $imap = Mail::IMAPClient->new(
      Server => $imaphost, User => $login, Password => $pass, Uid => 1
  );

  $imap->select("demo");

  my $msgs = $imap->search("ALL");
  for my $h (

   # get the Subject and Date from every message in folder "demo" the
   # first arg is a reference to an array listing all messages in the
   # folder (which is what gets returned by the $imap->search("ALL")
   # method when called in scalar context) and the remaining arguments
   # are the fields to parse out The key is the message number, which
   # in this case we don't care about:

    values %{ $imap->parse_headers( $msgs , "Subject", "Date") } )
  {
      # $h is the value of each element in the hash ref returned
      # from parse_headers, and $h is also a reference to a hash.
      # We'll only print the first occurrence of each field because
      # we don't expect more than one Date: or Subject: line per
      # message.
      print map { "$_:\t$h->{$_}[0]\n"} keys %$h;
  }

=head2 recent

Example:

  my @recent = $imap->recent or warn "No recent msgs: $@\n";

The B<recent> method performs an IMAP SEARCH RECENT search against the
selected folder and returns an array of sequence numbers (or UID's, if
the L</Uid> parameter is true) of messages that are recent.

=head2 recent_count

Example:

  my $count = 0;
  defined($count = $imap->recent_count($folder))
    or die "Could not recent_count: $@\n";

The B<recent_count> method accepts as an argument a folder name.  It
returns the number of recent messages in the folder (as returned by
the IMAP client command "STATUS folder RECENT"), or C<undef> in the
case of an error.  The B<recent_count> method was contributed by Rob
Deker (deker@ikimbo.com).

=head2 noop

Example:

  $imap->noop or die "noop failed: $@\n";

The B<noop> method performs an IMAP NOOP command.  Per RFC3501 this
command does nothing and always succeeds.  However, if a connection
times out or other errors occur while communicating with the server,
this method can still fail.  This command can be used as a periodic
poll to check for (untagged) status updates (new messages, etc.) from
the server and also to reset any inactivity/auto-logout timers the
server may maintain.

=head2 reconnect

Example:

  $imap->noop or $imap->reconnect or die "noop failed: $@\n";

Attempt to reconnect if the IMAP connection unless $imap is already in
the IsConnected state.  This method calls L</connect> and optionally
L</select> if a Folder was previously selected.  On success, returns
the (same) $imap object.  On failure <undef> is returned and
L</LastError> is set.

Version note: method added in Mail::IMAPClient 3.17

=head2 rename

Example:

  $imap->rename($oldname,$nedwname)
    or die "Could not rename: $@\n";

The B<rename> method accepts two arguments: the name of an existing
folder, and a new name for the folder.  The existing folder will be
renamed to the new name using the RENAME IMAP client command.
B<rename> will return a true value if successful, or C<undef> if
unsuccessful.

=head2 restore_message

Example:

  $imap->restore_message(@msgs) or die "Could not restore_message: $@\n";

The B<restore_message> method is used to undo a previous
L</delete_message> operation (but not if there has been an intervening
L</expunge> or L</close>).  The IMAPClient object must be in
L</Selected> status to use the B<restore_message> method.

The B<restore_message> method accepts a list of arguments.  If the
L</Uid> parameter is not set to a true value, then each item in the
list should be either:

=over 4

=item >

a message sequence number,

=item >

a comma-separated list of message sequence numbers,

=item >

a reference to an array of message sequence numbers, or

=back

If the L</Uid> parameter is set to a true value, then each item in the
list should be either:

=over 4

=item >

a message UID,

=item >

a comma-separated list of UID's, or

=item >

a reference to an array of message UID's.

=back

The messages identified by the sequence numbers or UID's will have
their I<\Deleted> flags cleared, effectively "undeleting" the
messages.  B<restore_message> returns the number of messages it was
able to restore.

Note that B<restore_messages> is similar to calling
C<L</unset_flag>("\Deleted",@msgs)>, except that B<restore_messages>
returns a (slightly) more meaningful value. Also it's easier to type.

=head2 run

Example:

  $imap->run(@args) or die "Could not run: $@\n";

The B<run> method is provided to make those uncommon things
possible... however, we would like you to contribute the knowledge of
missing features with us.

The B<run> method excepts one or two arguments.  The first argument is
a string containing an IMAP Client command, including a tag and all
required arguments.  The optional second argument is a string to look
for that will indicate success.  (The default is C</OK.*/>).  The
B<run> method returns an array (or arrayref in scalar context) of
output lines from the command, which you are free to parse as you see
fit.

The B<run> method does not do any syntax checking, other than
rudimentary checking for a tag.

When B<run> processes the command, it increments the transaction count
and saves the command and responses in the History buffer in the same
way other commands do.  However, it also creates a special entry in
the History buffer named after the tag supplied in the string passed
as the first argument.  If you supply a numeric value as the tag then
you may risk overwriting a previous transaction's entry in the History
buffer.

If you want the control of B<run> but you don't want to worry about
tags then see L</"tag_and_run">, below.

=head2 search

Example:

  my $msgs1 = $imap->search(@args);
  if ($msgs) {
      print "search matches: @$msgs1";
  }
  else {
      warn "Error in search: $@\n" if $@;
  }

  # or  note: be sure to quote string properly
  my $msgs2 = $imap->search( \( $imap->Quote($msgid), "FROM", q{"me"} ) )
    or warn "search failed: $@\n";

  # or  note: be sure to quote string properly
  my $msgs3 = $imap->search('TEXT "string not in mailbox"')
    or warn "search failed: $@\n";

The B<search> method implements the SEARCH IMAP client command.  Any
arguments supplied to B<search> are prefixed with a space then
appended to the SEARCH IMAP client command.  The SEARCH IMAP client
command allows for many options and arguments.  See RFC3501 for
details.

As of version 3.17 B<search> tries to "DWIM" by automatically quoting
things that likely need quotes when the words do not match any of the
following:

    ALL ANSWERED BCC BEFORE BODY CC DELETED DRAFT FLAGGED
    FROM HEADER KEYWORD LARGER NEW NOT OLD ON OR RECENT
    SEEN SENTBEFORE SENTON SENTSINCE SINCE SMALLER SUBJECT
    TEXT TO UID UNANSWERED UNDELETED UNDRAFT UNFLAGGED
    UNKEYWORD UNSEEN

The following options exist to avoid the automatic quoting (note:
caller is responsible for verifying the data sent in these cases is
properly escaped/quoted):

=over 4

=item *

specify a single string/argument in the call to search.

=item *

specify args as scalar references (SCALAR) and the values of those
SCALAR refs will be passed along as-is.

=back

The B<search> method returns an array containing sequence numbers of
messages that passed the SEARCH IMAP client command's search criteria.
If the L</Uid> parameter is true then the array will contain message
UID's.  If B<search> is called in scalar context then a pointer to the
array will be passed, instead of the array itself.  If no messages
meet the criteria then B<search> returns an empty list (when in list
context) or C<undef> (in scalar context).

Since a valid, successful search can legitimately return zero matches,
you may wish to distinguish between a search that correctly returns
zero hits and a search that has failed for some other reason (i.e.
invalid search parameters).  Therefore, the C<$@> variable will always
be cleared before the I<SEARCH> command is issued to the server, and
will thus remain empty unless the server gives a I<BAD> or I<NO>
response to the I<SEARCH> command.

=head2 see

Example:

  $imap->see(@msgs) or die "Could not see: $@\n";

The B<see> method accepts a list of one or more messages sequence
numbers, or a single reference to an array of one or more message
sequence numbers, as its argument(s).  It then sets the I<\Seen> flag
for those message(s).  Of course, if the L</Uid> parameter is set to a
true value then those message sequence numbers had better be unique
message id's, but then you already knew that, didn't you?

Note that specifying C<$imap-E<gt>see(@msgs)> is just a shortcut for
specifying C<$imap-E<gt>L</set_flag>("Seen",@msgs)>.

=head2 seen

Example:

  my @seenMsgs = $imap->seen or warn "No seen msgs: $@\n";

The B<seen> method performs an IMAP SEARCH SEEN search against the
selected folder and returns an array of sequence numbers of messages
that have already been seen (ie their I<\Seen> flag is set).  If the
L</Uid> parameter is true then an array of message UID's will be
returned instead.  If called in scalar context than a reference to the
array (rather than the array itself) will be returned.

=head2 select

Example:

  $imap->select($folder) or die "Could not select: $@\n";

The B<select> method selects a folder and changes the object's state
to I<Selected>.  It accepts one argument, which is the name of the
folder to select.

=head2 selectable

Example:

  foreach my $f ( grep( $imap->selectable($_), $imap->folders ) ) {
      $imap->select($f);
  }

The B<selectable> method accepts one value, a folder name, and returns
true if the folder is selectable or false if it is not selectable.

=head2 sentbefore

Example:

  my @msgs = $imap->sentbefore($Rfc3501_date)
    or warn "Could not find any msgs sent before $Rfc3501_date: $@\n";

The B<sentbefore> method works just like L</"sentsince">, below,
except it searches for messages that were sent before the date
supplied as an argument to the method.

=head2 senton

Example:

  my @msgs = $imap->senton($Rfc3501_date)
    or warn "Could not find any messages sent on $Rfc3501_date: $@\n";

The B<senton> method works just like L</"sentsince">, below, except it
searches for messages that were sent on the exact date supplied as an
argument to the method.

=head2 sentsince

Example:

  my @msgs = $imap->sentsince($Rfc3501_date)
    or warn "Could not find any messages sent since $Rfc3501_date: $@\n";

The B<sentsince> method accepts one argument, a date in either epoch
time format (seconds since 1/1/1970, or as output by
L<time|perlfunc/time> and as accepted by
L<localtime|perlfunc/localtime>) or in the I<date_text> format as
defined in RFC3501 (dd-Mon-yyyy, where Mon is the English-language
three-letter abbreviation for the month).

It searches for items in the currently selected folder for messages
sent since the day whose date is provided as the argument.  It uses
the RFC822 I<Date:> header to determine the I<sentsince> date.
(Actually, it the server that uses the I<Date:> header; this
documentation just assumes that the date is coming from the I<Date:>
header because that's what RFC3501 dictates.)

In the case of arguments supplied as a number of seconds, the returned
result list will include items sent on or after that day, regardless
of whether they arrived before the specified time on that day.  The
IMAP protocol does not support searches at a granularity finer than a
day, so neither do I.  On the other hand, the only thing I check for
in a I<date_text> argument is that it matches the pattern
C</\d\d-\D\D\D-\d\d\d\d/> (notice the lack of anchors), so if your
server lets you add something extra to a I<date_text> string then so
will Mail::IMAPClient.

If you'd like, you can use the L</Rfc3501_date> method to convert from
epoch time (as returned by L<time|perlfunc/time>) into an RFC3501 date
specification.

=head2 separator

Example:

  my $sepChar = $imap->separator(@args)
    or die "Could not get separator: $@\n";

The B<separator> method returns the character used as a separator
character in folder hierarchies.  On UNIX-based servers, this is often
but not necessarily a forward slash (/).  It accepts one argument, the
name of a folder whose hierarchy's separator should be returned.  If
no folder name is supplied then the separator for the INBOX is
returned, which probably is good enough.

If you want your programs to be portable from IMAP server brand X to
IMAP server brand Y, then you should never use hard-coded separator
characters to specify subfolders.  (In fact, it's even more
complicated than that, since some server don't allow any subfolders at
all, some only allow subfolders under the "INBOX" folder, and some
forbid subfolders in the inbox but allow them "next" to the inbox.
Furthermore, some server implementations do not allow folders to
contain both subfolders and mail messages; other servers allow this.)

=head2 set_flag

Example:

  $imap->set_flag( "Seen", @msgs )
    or die "Could not set flag: $@\n";

The B<set_flag> method accepts the name of a flag as its first
argument and a list of one or more messages sequence numbers, or a
single reference to an array of one or more message sequence numbers,
as its next argument(s).  It then sets the flag specified for those
message(s).  Of course, if the L</Uid> parameter is set to a true
value then those message sequence numbers had better be unique message
id's, just as you'd expect.

Note that when specifying the flag in question, the preceding
backslash (\) is entirely optional.  (For you, that is.
Mail::IMAPClient still has remember to stick it in there before
passing the command to the server if the flag is one of the reserved
flags specified in RFC3501.  This is in fact so important that the
method checks its argument and adds the backslash when necessary,
which is why you don't have to worry about it overly much.)

=head2 setacl

Example:

  $imap->setacl( $folder, $userid, $aclstring )
    or die "Could not set acl: $@\n";

The B<setacl> method accepts three input arguments, a folder name, a
user id (or authentication identifier, to use the terminology of
RFC2086), and an access rights modification string.  See RFC2086 for
more information.  (This is somewhat experimental and its
implementation may change.)

=head2 since

Example:

  my @msgs = $imap->since($date)
    or warn "Could not find any messages since $date: $@\n";

The B<since> method accepts a date in either epoch format (seconds
since 1/1/1970, or as output by L<perlfunc/time> and as accepted by
L<perlfunc/localtime>) or in the I<date_text> format as defined in
RFC3501 (dd-Mon-yyyy, where Mon is the English-language three-letter
abbreviation for the month).  It searches for items in the currently
selected folder for messages whose internal dates are on or after the
day whose date is provided as the argument.  It uses the internal
system date for a message to determine if that message was sent since
the given date.

In the case of arguments supplied as a number of seconds, the returned
result list will include items whose internal date is on or after that
day, regardless of whether they arrived before the specified time on
that day.

If B<since> is called in a list context then it will return a list of
messages meeting the I<SEARCH SINCE> criterion, or an empty list if no
messages meet the criterion.

If B<since> is called in a scalar context then it will return a
reference to an array of messages meeting the I<SEARCH SINCE>
criterion, or C<undef> if no messages meet the criterion.

Since B<since> is a front-end to L</search>, some of the same rules
apply.  For example, the C<$@> variable will always be cleared before
the I<SEARCH> command is issued to the server, and will thus remain
empty unless the server gives a I<BAD> or I<NO> response to the
I<SEARCH> command.

=head2 size

Example:

  my $size = $imap->size($msgId)
    or die "Could not find size of message $msgId: $@\n";

The B<size> method accepts one input argument, a sequence number (or
message UID if the L</Uid> parameter is true).  It returns the size of
the message in the currently selected folder with the supplied
sequence number (or UID).  The IMAPClient object must be in a
I<Selected> state in order to use this method.

=head2 sort

Example:

  my @msgs = $imap->sort(@args);
  warn "Error in sort: $@\n" if $@;

The B<sort> method is just like the L</search> method, only different.
It implements the SORT extension as described in
F<http://search.ietf.org/internet-drafts/draft-ietf-imapext-sort-10.txt>.
It would be wise to use the L</has_capability> method to verify that
the SORT capability is available on your server before trying to use
the B<sort> method.  If you forget to check and you're connecting to a
server that doesn't have the SORT capability then B<sort> will return
undef.  L</LastError> will then say you are "BAD".  If your server
doesn't support the SORT capability then you'll have to use L</search>
and then sort the results yourself.

The first argument to B<sort> is a space-delimited list of sorting
criteria.  The Internet Draft that describes SORT requires that this
list be wrapped in parentheses, even if there is only one sort
criterion.  If you forget the parentheses then the B<sort> method will
add them.  But you have to forget both of them, or none.  This isn't
CMS running under VM!

The second argument is a character set to use for sorting.  Different
character sets use different sorting orders, so this argument is
important.  Since all servers must support UTF-8 and US-ASCII if they
support the SORT capability at all, you can use one of those if you
don't have some other preferred character set in mind.

The rest of the arguments are searching criteria, just as you would
supply to the L</search> method.  These are all documented in RFC3501.
If you just want all of the messages in the currently selected folder
returned to you in sorted order, use I<ALL> as your only search
criterion.

The B<sort> method returns an array containing sequence numbers of
messages that passed the SORT IMAP client command's search criteria.
If the L</Uid> parameter is true then the array will contain message
UID's.  If B<sort> is called in scalar context then a pointer to the
array will be passed, instead of the array itself.  The message
sequence numbers or unique identifiers are ordered according to the
sort criteria specified.  The sort criteria are nested in the order
specified; that is, items are sorted first by the first criterion, and
within the first criterion they are sorted by the second criterion,
and so on.

The sort method will clear C<$@> before attempting the I<SORT>
operation just as the L</search> method does.

=head2 starttls

Example:

  $imap->starttls() or die "starttls failed: $@\n";

The B<starttls> method accepts no arguments.  This method is used to
upgrade an exiting connection which is not authenticated to a TLS/SSL
connection by using the IMAP STARTTLS command followed by using the
B<start_SSL> class method from L<IO::Socket::SSL> to do the necessary
TLS negotiation.  The negotiation is done in a blocking fashion with a
default B<Timeout> of 30 seconds.  The arguments used in the call to
B<start_SSL> can be controlled by setting the Mail::IMAPClient
L</Starttls> attribute to an ARRAY reference containing the desired
arguments.

Version note: method added in Mail::IMAPClient 3.22

=head2 status

Example:

  my @rawdata = $imap->status( $folder, qw/(Messages)/ )
    or die "Error obtaining status: $@\n";

The B<status> method accepts one argument, the name of a folder (or
mailbox, to use RFC3501's terminology), and returns an array
containing the results of running the IMAP STATUS client command
against that folder.  If additional arguments are supplied then they
are appended to the IMAP STATUS client command string, separated from
the rest of the string and each other with spaces.

If B<status> is not called in an array context then it returns a
reference to an array rather than the array itself.

The B<status> method should not be confused with the B<Status> method
(with an uppercase 'S'), which returns information about the
IMAPClient object.  (See the section labeled L</"Status Methods">,
below).

=head2 store

Example:

  $imap->store(@args) or die "Could not store: $@\n";

The B<store> method accepts a message sequence number or
comma-separated list of message sequence numbers as a first argument,
a message data item name, and a value for the message data item.
Currently, data items are the word "FLAGS" followed by a space and a
list of flags (in parens).  The word "FLAGS" can be modified by
prefixing it with either a "+" or a "-" (to indicate "add these flags"
or "remove these flags") and by suffixing it with ".SILENT" (which
reduces the amount of output from the server; very useful with large
message sets).  Normally you won't need to call B<store> because there
are oodles of methods that will invoke store for you with the correct
arguments.  Furthermore, these methods are friendlier and more
flexible with regards to how you specify your arguments.  See for
example L</see>, L</deny_seeing>, L</delete_message>, and
L</restore_message>.  Or L</mark>, L</unmark>, L</set_flag>, and
L</unset_flag>.

=head2 subject

Example:

  my $subject = $imap->subject($msg);

The B<subject> method accepts one argument, a message sequence number
(or a message UID, if the I<Uid> parameter is true).  The text in the
"Subject" header of that message is returned (without the "Subject: "
prefix).  This method is a short-cut for:

  my $subject = $imap->get_header($msg, "Subject");

=head2 subscribed

Example:

  my @subscribedFolders = $imap->subscribed
    or warn "Could not find subscribed folders: $@\n";

The B<subscribed> method works like the B<folders> method, above,
except that the returned list (or array reference, if called in scalar
context) contains only the subscribed folders.

Like L</folders>, you can optionally provide a prefix argument to the
B<subscribed> method.

=head2 tag_and_run

Example:

  my $output = $imap->tag_and_run(@args)
    or die "Could not tag_and_run: $@\n";

The B<tag_and_run> method accepts one or two arguments.  The first
argument is a string containing an IMAP Client command, without a tag
but with all required arguments.  The optional second argument is a
string to look for that will indicate success (without pattern
delimiters).  The default is C<OK.*>.

The B<tag_and_run> method will prefix your string (from the first
argument) with the next transaction number and run the command.  It
returns an array of output lines from the command, which you are free
to parse as you see fit.  Using this method instead of B<run> (above)
will free you from having to worry about handling the tags (and from
worrying about the side affects of naming your own tags).

=head2 uidexpunge

Example:

  $imap->uidexpunge(@uids) or die "Could not uidexpunge: $@\n";

The B<uidexpunge> method implements the UID EXPUNGE IMAP (RFC4315
UIDPLUS ext) client command to permanently remove all messages that
have the \Deleted flag set and have a UID that is included in the list
of UIDs.

B<uidexpunge> returns an array or arrayref (scalar context) of output
lines returned from the UID EXPUNGE command.

B<uidexpunge> returns undef on failure.

If the server does not support the UIDPLUS extension, this method
returns undef.

=head2 uidnext

Example:

  my $nextUid = $imap->uidnext($folder) or die "Could not uidnext: $@\n";

The B<uidnext> method accepts one argument, the name of a folder, and
returns the numeric string that is the next available message UID for
that folder.

=head2 thread

Example:

  my $thread = $imap->thread($algorithm, $charset, @search_args );

The B<thread> method accepts zero to three arguments.  The first
argument is the threading algorithm to use, generally either
I<ORDEREDSUBJECT> or I<REFERENCES>.  The second argument is the
character set to use, and the third argument is the set of search
arguments to use.

If the algorithm is not supplied, it defaults to I<REFERENCES> if
available, or I<ORDEREDSUBJECT> if available.  If neither of these is
available then the B<thread> method returns undef.

If the character set is not specified it will default to I<UTF-8>.

If the search arguments are not specified, the default is I<ALL>.

If B<thread> is called for an object connected to a server that does
not support the THREADS extension then the B<thread> method will
return C<undef>.

The B<threads> method will issue the I<THREAD> command as defined in
F<http://www.ietf.org/internet-drafts/draft-ietf-imapext-thread-11.txt>.
It returns an array of threads.  Each element in the array is either a
message id or a reference to another array of (sub)threads.

If the L</Uid> parameter is set to a true value then the message id's
returned in the thread structure will be message UID's.  Otherwise
they will be message sequence numbers.

=head2 uidvalidity

Example:

  my $validity = $imap->uidvalidity($folder)
    or die "Could not uidvalidity: $@\n";

The B<uidvalidity> method accepts one argument, the name of a folder,
and returns the numeric string that is the unique identifier validity
value for the folder.

=head2 unmark

Example:

  $imap->unmark(@msgs) or die "Could not unmark: $@\n";

The B<unmark> method accepts a list of one or more messages sequence
numbers, or a single reference to an array of one or more message
sequence numbers, as its argument(s).  It then unsets the I<\Flagged>
flag for those message(s).  Of course, if the L</Uid> parameter is set
to a true value then those message sequence numbers should really be
unique message id's.

Note that specifying C<$imap-E<gt>unmark(@msgs)> is just a shortcut
for specifying C<$imap-E<gt>unset_flag("Flagged",@msgs)>.

Note also that the I<\Flagged> flag is just one of many possible
flags.  This is a little confusing, but you'll have to get used to the
idea that among the reserved flags specified in RFC3501 is one name
I<\Flagged>.  There is no specific meaning for this flag; it means
whatever the mailbox owner (or delegate) wants it to mean when it is
turned on.

=head2 unseen

Example:

  my @unread = $imap->unseen or warn "Could not find unseen msgs: $@\n";

The B<unseen> method performs an IMAP SEARCH UNSEEN search against the
selected folder and returns an array of sequence numbers of messages
that have not yet been seen (ie their I<\Seen> flag is not set).  If
the L</Uid> parameter is true then an array of message UID's will be
returned instead.  If called in scalar context than a pointer to the
array (rather than the array itself) will be returned.

Note that when specifying the flag in question, the preceding
backslash (\) is entirely optional.

=head2 unseen_count

Example:

  foreach my $f ($imap->folders) {
      print "The $f folder has ",
        $imap->unseen_count($f)||0, " unseen messages.\n";
  }

The B<unseen_count> method accepts the name of a folder as an argument
and returns the number of unseen messages in that folder.  If no
folder argument is provided then it returns the number of unseen
messages in the currently selected Folder.

=head2 unset_flag

Example:

  $imap->unset_flag( "\Seen", @msgs )
    or die "Could not unset_flag: $@\n";

The B<unset_flag> method accepts the name of a flag as its first
argument and a list of one or more messages sequence numbers, or a
single reference to an array of one or more message sequence numbers,
as its next argument(s).  It then unsets the flag specified for those
message(s).  Of course, if the L</Uid> parameter is set to a true
value then those message sequence numbers had better be unique message
id's, just as you'd expect.

=head1 Other IMAP Client Commands

Until release C<2.99>, when you called a method which did not exist,
they where automatically translated into an IMAP call with the same
name via an AUTOLOAD hack.  This "feature" was removed for various
reasons: people made typos in the capitalization of method names, and
the program still seemed to work correctly.  Besides, it blocked
further development of this module, because people did not contribute
their private extensions to the protocol implementation.

=head2 copy($msg, $folder)

Copy a message from the currently selected folder in the folder whose
name is in C<$folder>

=head2 subscribe($folder)

Subscribe to a folder

B<CAUTION:> Once again, remember to quote your quotes (or use the
L</Quote> method) if you want quotes to be part of the IMAP command
string.

You can also use the default method to override the behavior of
implemented IMAP methods by changing the case of the method name,
preferably to all-uppercase so as not to conflict with the Class
method and accessor method namespace.  For example, if you don't want
the L</search> method's behavior (which returns a list of message
numbers) but would rather have an array of raw data returned from your
L</search> operation, you can issue the following snippet:

  my @raw = $imap->SEARCH("SUBJECT","Whatever...");

which is slightly more efficient than the equivalent:

  $imap->search("SUBJECT","Whatever...");
  my @raw = $imap->Results;

Of course you probably want the search results tucked nicely into a
list for you anyway, in which case you might as well use the
L</search> method.

=head1 Parameters

There are several parameters that influence the behavior of an
IMAPClient object.  Each is set by specifying a named value pair
during new method invocation as follows:

  my $imap = Mail::IMAPClient->new ( parameter  => "value",
      parameter2 => "value",
      ...
  );

Parameters can also be set after an object has been instantiated by
using the parameter's eponymous accessor method like this:

  my $imap = Mail::IMAPClient->new;
     $imap->parameter( "value");
     $imap->parameter2("value");

The eponymous accessor methods can also be used without arguments to
obtain the current value of the parameter as follows:

  my $imap = Mail::IMAPClient->new;
     $imap->parameter( "value");
     $imap->parameter2("value");

    ...    # A whole bunch of awesome Perl code, omitted for brevity

  my $forgot  = $imap->parameter;
  my $forgot2 = $imap->parameter2;

Note that in these examples I'm using 'parameter' and 'parameter2' as
generic parameter names.  The IMAPClient object doesn't actually have
parameters named 'parameter' and 'parameter2'.  On the contrary, the
available parameters are:

=head2 Authmechanism

Example:

  $imap->Authmechanism("CRAM-MD5");
  # or
  my $authmech = $imap->Authmechanism();

If specified, the I<Authmechanism> causes the specified authentication
mechanism to be used whenever Mail::IMAPClient would otherwise invoke
B<login>.  If the value specified for the I<Authmechanism> parameter
is not a valid authentication mechanism for your server then you will
never ever be able to log in again for the rest of your Perl script,
probably.  So you might want to check, like this:

  my $authmech = "CRAM-MD5";
  $imap->has_capability($authmech) and $imap->Authmechanism($authmech);

Of course if you know your server supports your favorite authentication
mechanism then you know, so you can then include your I<Authmechanism>
with your B<new> call, as in:

  my $imap = Mail::IMAPClient->new(
      User    => $user,
      Passord => $passord,
      Server  => $server,
      Authmechanism  => $authmech,
      %etc
  );

If I<Authmechanism> is supplied but I<Authcallback> is not then you
had better be supporting one of the authentication mechanisms that
Mail::IMAPClient supports "out of the box" (such as CRAM-MD5).

=head2 Authcallback

Example:

  $imap->Authcallback( \&callback );

This specifies a default callback to the default authentication
mechanism (see L</Authmechanism>, above).  Together, these two methods
replace automatic calls to login with automatic calls that look like
this (sort of):

  $imap->authenticate($imap->Authmechanism,$imap->Authcallback);

If I<Authmechanism> is supplied but I<Authcallback> is not then you
had better be supporting one of the authentication mechanisms that
Mail::IMAPClient supports "out of the box" (such as CRAM-MD5).

=head2 Authuser

The I<Authuser> parameter is used by the DIGEST-MD5 L</Authmechanism>.

Typically when you authenticate the username specified in the User
parameter is used.  However, when using the DIGEST-MD5
I<Authmechanism> the I<Authuser> can be used to specify a different
username for the login.

This can be useful to mark messages as seen for the I<Authuser> if you
don't know the password of the user as the seen state is often a
per-user state.

=head2 Buffer

Example:

  $Buffer = $imap->Buffer();
  # or:
  $imap->Buffer($new_value);

The I<Buffer> parameter sets the size of a block of I/O.  It is
ignored unless L</Fast_io>, below, is set to a true value (the
default), or unless you are using the L</migrate> method.  It's value
should be the number of bytes to attempt to read in one I/O operation.
The default value is 4096.

When using the L</migrate> method, you can often achieve dramatic
improvements in throughput by adjusting this number upward.  However,
doing so also entails a memory cost, so if set too high you risk
losing all the benefits of the L</migrate> method's chunking
algorithm.  Your program can thus terminate with an "out of memory"
error and you'll have no one but yourself to blame.

Note that, as hinted above, the I<Buffer> parameter affects the
behavior of the L</migrate> method regardless of whether you have
L</Fast_io> turned on.  Believe me, you don't want to go around
migrating tons of mail without using buffered I/O!

=head2 Clear

Example:

  $Clear = $imap->Clear();
  # or:
  $imap->Clear($integer);

The name of this parameter, for historical reasons, is somewhat
misleading.  It should be named I<Wrap>, because it specifies how many
transactions are stored in the wrapped history buffer.  But it didn't
always work that way; the buffer used to actually get cleared.  The
name though remains the same in the interests of backwards
compatibility.

I<Clear> specifies that the object's history buffer should be wrapped
after every I<n> transactions, where I<n> is the value specified for
the I<Clear> parameter.  Calling the eponymous B<Clear> method without
an argument will return the current value of the I<Clear> parameter
but will not cause clear the history buffer to wrap.

Setting I<Clear> to 0 turns off automatic history buffer wrapping, and
setting it to 1 turns off the history buffer facility (except for the
last transaction, which cannot be disabled without breaking the
IMAPClient module).  Setting I<Clear> to 0 will not cause an immediate
clearing of the history buffer; setting it to 1 (or any other number)
will (except of course for that inevitable last transaction).

The default I<Clear> value is set to five (5) in order to conserve
memory.

=head2 Compress

If set, Mail::IMAPClient attempts to enable use of the RFC4978
COMPRESS DEFLATE extension.  This requires that the server supports
this CAPABILITY.  This attribute can be set to a true value to enable
or an ARRAYREF to control the arguments used in the call to
Compress::Zlib::deflateInit().

Mail::IMAPClient will automatically use L<Compress::Zlib> to
deflate/inflate the data to/from the server.  This attribute is used
in the L</login> method.

See also L</compress> and L</capability>.

Version note: attribute added in Mail::IMAPClient 3.30

=head2 Debug

Example:

  $Debug = $imap->Debug();
  # or:
  $imap->Debug($true_or_false);

Sets the debugging flag to either a true or false value.  Can be
supplied with the L</new> method call or separately by calling the
B<Debug> object method.  Use of this parameter is strongly recommended
when debugging scripts and required when reporting bugs.

=head2 Debug_fh

Example:

  $Debug_fh = $imap->Debug_fh();
  # or:
  $imap->Debug_fh($fileHandle);

Specifies the file handle to which debugging information should be
printed.  It can either a file handle object reference or a file handle
glob.  The default is to print debugging info to STDERR.

For example, you can:

  use Mail::IMAPClient;
  use IO::File;
  # set $user, $pass, and $server here
  my $dh = IO::File->new(">debugging.output")
    or die "Can't open debugging.output: $!\n";
  my $imap = Mail::IMAPClient->new(
      User=>$user, Password=>$pass, Server=>$server, Debug=>1, Debug_fh => $dh
  );

which is the same as:

  use Mail::IMAPClient;
  use IO::File;
  # set $user, $pass, and $server here
  my $imap = Mail::IMAPClient->new(
      User     => $user,
      Password => $pass,
      Server   => $server,
      Debug    => "yes, please",
      Debug_fh => IO::File->new(">debugging.output")
        || die "Can't open debugging.output: $!\n"
  );

You can also:

  use Mail::IMAPClient;
  # set $user, $pass, and $server here
  open(DBG,">debugging.output")
    or die "Can't open debugging.output: $!\n";
  my $imap = Mail::IMAPClient->new(
    User=>$user, Password=>$pass, Server=>$server, Debug=> 1, Debug_fh => *DBG
  );

Specifying this parameter is not very useful unless L</Debug> is set
to a true value.

=head2 Domain

The I<Domain> parameter is used by the NTLM L</Authmechanism>.  The
domain is an optional parameter for NTLM authentication.

=head2 EnableServerResponseInLiteral

Removed in 2.99_01 (now autodetect)

=head2 Fast_io

Example:

  $Fast_io = $imap->Fast_io();
  # or:
  $imap->Fast_io($true_or_false);

The I<Fast_io> parameter controls whether or not the Mail::IMAPClient
object will attempt to use non-blocking I/O on the IMAP socket.  It is
turned on by default (unless the caller provides the socket to be
used).

See also L</Buffer>.

=head2 Folder

Example:

  $Folder = $imap->Folder();
  # or:
  $imap->Folder($new_value);

The I<Folder> parameter returns the name of the currently-selected
folder (in case you forgot).  It can also be used to set the name of
the currently selected folder, which is completely unnecessary if you
used the L</select> method (or L</select>'s read-only equivalent, the
L</examine> method) to select it.

Note that setting the I<Folder> parameter does not automatically
select a new folder; you use the L</select> or L</examine> object
methods for that.  Generally, the I<Folder> parameter should only be
queried (by using the no-argument form of the B<Folder> method).  You
will only need to set the I<Folder> parameter if you use some
mysterious technique of your own for selecting a folder, which you
probably won't do.

=head2 Ignoresizeerrors

Certain (caching) servers, like Exchange 2007, often report the wrong
message size.  Instead of chopping the message into a size that it
fits the specified size, the reported size will be simply ignored when
this parameter is set to C<1>.

=head2 Keepalive

Some firewalls and network gear like to timeout connections
prematurely if the connection sits idle.  The B<Keepalive> parameter,
when set to a true value, affects the behavior of L</new> and
L</Socket> by enabling SO_KEEPALIVE on the socket.

Version note: attribute added in Mail::IMAPClient 3.17

=head2 Maxcommandlength

The B<Maxcommandlength> attribute is used by fetch() to limit length
of commands sent to a server.  The default is 1000 chars, following
the recommendation of RFC2683 section 3.2.1.5.

B<Note>: this attribute should also be used for several other methods
but this has not yet been implemented please feel free to file bugs
for methods where you run into problems with this.

This attribute should remove the need for utilities like imapsync to
create their own split() functions and instead allows Mail::IMAPClient
to DWIM.

In practice, this parameter has proven to be useful to overcome a
limit of 8000 octets for UW-IMAPD and 16384 octets for Courier/Cyrus
IMAP servers.

Version note: attribute added in Mail::IMAPClient 3.17

=head2 Maxtemperrors

Example:

  $Maxtemperrors = $imap->Maxtemperrors();
  # or:
  $imap->Maxtemperrors($number);

The I<Maxtemperrors> parameter specifies the number of times a read or
write operation is allowed to fail on a "Resource Temporarily
Available" (e.g. EAGAIN) error.  The default setting is I<undef> which
means there is no limit.

Setting this parameter to the string "unlimited" (instead of undef) to
ignore "Resource Temporarily Unavailable" errors is deprecated.

B<Note>: This setting should be used with caution and may be removed
in a future release.  Setting this can cause methods to return to the
caller before data is received (and then handled) properly thereby
possibly then leaving the module in a bad state.  In the future, this
behavior may be changed in an attempt to avoid this situation.

=head2 Password

Example:

  $Password = $imap->Password();
  # or:
  $imap->Password($new_value);

Specifies the password to use when logging into the IMAP service on
the host specified in the I<Server> parameter as the user specified in
the I<User> parameter.  Can be supplied with the B<new> method call or
separately by calling the B<Password> object method.

If I<Server>, I<User>, and I<Password> are all provided to the L</new>
method, then the newly instantiated object will be connected to the
host specified in I<Server> (at either the port specified in I<Port>
or the default port 143) and then logged on as the user specified in
the I<User> parameter (using the password provided in the I<Password>
parameter).  See the discussion of the L</"new"> method, below.

=head2 Peek

Example:

  $Peek = $imap->Peek();
  # or:
  $imap->Peek($true_or_false);

Setting I<Peek> to a true value will prevent the L</body_string>,
L</message_string> and L</message_to_file> methods from automatically
setting the I<\Seen> flag.  Setting L</"Peek"> to 0 (zero) will force
L</"body_string">, L</"message_string">, L</"message_to_file">, and
L</"parse_headers"> to always set the I<\Seen> flag.

The default is to set the seen flag whenever you fetch the body of a
message but not when you just fetch the headers.  Passing I<undef> to
the eponymous B<Peek> method will reset the I<Peek> parameter to its
pristine, default state.

=head2 Port

Example:

  $Port = $imap->Port();
  # or:
  $imap->Port($new_value);

Specifies the port on which the IMAP server is listening.  A default
value of 993 (if L</Ssl> is true) or 143 is set during a call to
L</connect> if no value is provided by the caller.  This argument can
be supplied with the L</new> method call or separately by calling the
L</Port> object method.

=head2 Prewritemethod

I<Prewritemethod> parameter should contain a reference to a subroutine
that will do "special things" to data before it is sent to the IMAP
server (such as encryption or signing).

This method will be called immediately prior to sending an IMAP client
command to the server.  Its first argument is a reference to the
I<Mail::IMAPClient> object and the second argument is a string
containing the command that will be sent to the server.  Your
I<Prewritemethod> should return a string that has been signed or
encrypted or whatever; this returned string is what will actually be
sent to the server.

Your I<Prewritemethod> will probably need to know more than this to do
whatever it does.  It is recommended that you tuck all other pertinent
information into a hash, and store a reference to this hash somewhere
where your method can get to it, possibly in the I<Mail::IMAPClient>
object itself.

Note that this method should not actually send anything over the
socket connection to the server; it merely converts data prior to
sending.

See also L</Readmethod>.

=head2 Ranges

Example:

  $imap->Ranges(1);
  # or:
  my $search = $imap->search(@search_args);
  if ( $imap->Ranges) { # $search is a MessageSet object
      print "This is my condensed search result: $search\n";
      print "This is every message in the search result: ",
        join(",",@$search),"\n;
  }

If set to a true value, then the L</search> method will return a
L<Mail::IMAPClient::MessageSet> object if called in a scalar context,
instead of the array reference that B<fetch> normally returns when
called in a scalar context.  If set to zero or if undefined, then
B<search> will continue to return an array reference when called in
scalar context.

This parameter has no affect on the B<search> method when B<search>
is called in a list context.

=head2 RawSocket

Example:
        $socket = $imap->RawSocket;
        # or:
        $imap->RawSocket($socketh);

The I<RawSocket> method can be used to obtain the socket handle of the
current connection (say, to do I/O on the connection that is not
otherwise supported by Mail::IMAPClient) or to replace the current
socket with a new handle (for instance an SSL handle, see
L<IO::Socket::SSL>, but be sure to see the L</Socket> method as well).

If you supply a socket handle yourself, either by doing something like:

        $imap=Mail::IMAPClient->new(RawSocket => $sock, User => ... );

or by doing something like:

        $imap = Mail::IMAPClient->new(User => $user,
                    Password => $pass, Server => $host);
        # blah blah blah
        $imap->RawSocket($ssl);

then it will be up to you to establish the connection AND to
authenticate, either via the L</login> method, or the fancier
L</authenticate>, or, since you know so much anyway, by just doing raw
I/O against the socket until you're logged in.  If you do any of this
then you should also set the L</State> parameter yourself to reflect
the current state of the object (i.e. Connected, Authenticated, etc).

Note that no operation will be attempted on the socket when this
method is called.  In particular, after the TCP connections towards
the IMAP server is established, the protocol mandates the server to
send an initial greeting message, and you will have to explicitly cope
with this message before doing any other operation, e.g. trying to
call L</login>. Caveat emptor.

For a more DWIM approach to setting the socket see L</Socket>.

=head2 Readmethod

Example:

  $imap->Readmethod(   # IMAP, HANDLE, BUFFER, LENGTH, OFFSET
      sub {
          my ( $self, $handle, $buffer, $count, $offset ) = @_;
          my $rc = sysread( $handle, $$buffer, $count, $offset );
          # do something useful here...
      }
  );

B<Readmethod> should contain a reference to a subroutine that will
replace sysread.  The subroutine will be passed the following
arguments: first the used Mail::IMAPClient object.  Second, a
reference to a socket.  Third, a reference to a scalar variable into
which data is read (BUFFER). The data placed here should be "finished
data", so if you are decrypting or removing signatures then be sure to
do that before you place data into this buffer.  Fourth, the number of
bytes requested to be read; the LENGTH of the request.  Lastly, the
OFFSET into the BUFFER where the data should be read.  If not supplied
it should default to zero.

Note that this method completely replaces reads from the connection
to the server, so if you define one of these then your subroutine will
have to actually do the read.  It is for things like this that we have
the L</Socket> parameter and eponymous accessor method.

Your I<Readmethod> will probably need to know more than this to do
whatever it does.  It is recommended that you tuck all other pertinent
information into a hash, and store a reference to this hash somewhere
where your method can get to it, possibly in the I<Mail::IMAPClient>
object itself.

See also L</Prewritemethod>.

=head2 Readmoremethod

B<Readmoremethod> should contain a reference to a subroutine that will
replace/enhance the behavior of the internal _read_more() method.  The
subroutine will be passed the following arguments: first the used
Mail::IMAPClient object.  Second, a reference to a socket.  Third, a
timeout value which is used as the timeout value for CORE::select() by
default.  Depending upon changes/features introduced by Readmethod
changes may be required here.

Version note: attribute added in Mail::IMAPClient 3.30

=head2 Reconnectretry

If an IMAP connection sits idle too long, the connection may be closed
by the server or firewall, etc.  The B<Reconnectretry> parameter, when
given a positive integer value, will cause Mail::IMAPClient to
retrying IMAP commands up to X times when an EPIPE or ECONNRESET error
occurs.  This is disabled (0) by default.

See also L</Keepalive>

Version note: attribute added in Mail::IMAPClient 3.17

=head2 Server

Example:

  $Server = $imap->Server();
  # or:
  $imap->Server($hostname);

Specifies the hostname or IP address of the host running the IMAP
server.  If provided as part of the L</new> method call, then the new
IMAP object will automatically be connected at the time of
instantiation.  (See the L</new> method, below.) Can be supplied with
the L</new> method call or separately by calling the B<Server> object
method.

=head2 Showcredentials

Normally debugging output will mask the login credentials when the
plain text login mechanism is used.  Setting I<Showcredentials> to a
true value will suppress this, so that you can see the string being
passed back and forth during plain text login.  Only set this to true
when you are debugging problems with the IMAP LOGIN command, and then
turn it off right away when you're finished working on that problem.

Example:

  print "This is very risky!\n" if $imap->Showcredentials();
  # or:
  $imap->Showcredentials(0);    # mask credentials again

=head2 Socket

B<PLEASE NOTE> The semantics of this method has changed as of version
2.99_04 of this module.  If you need the old semantics use
L</RawSocket>.

Example:

  $Socket = $imap->Socket();
  # or:
  $imap->Socket($socket_fh);

The I<Socket> method can be used to obtain the socket handle of the
current connection.  This may be necessary to do I/O on the connection
that is not otherwise supported by Mail::IMAPClient) or to replace the
current socket with a new handle (for instance an SSL handle, see
IO::Socket::SSL).

If you supply a socket handle yourself, either by doing something like:

  $imap = Mail::IMAPClient->new( Socket => $sock, User => ... );

or by doing something like:

  $imap = Mail::IMAPClient->new(
    User => $user, Password => $pass, Server => $host
  );
  $imap->Socket($ssl);

then you are responsible for establishing the connection, i.e. make
sure that C<$ssl> in the example is a valid and connected socket.

This method is primarily used to provide a drop-in replacement for
IO::Socket::(INET|IP), used by L</connect> by default.  In fact, this
method is called by L</connect> itself after having established a
suitable IO::Socket::(INET|IP) socket connection towards the target
server; for this reason, this method also carries the normal
operations associated with L</connect>, namely:

=over 4

=item *

read the initial greeting message from the server;

=item *

call L</login> if the conditions apply (see L</connect> for details);

=item *

leave the I<Mail::IMAPClient> object in a suitable state.

=back

For these reasons, the following example will work "out of the box":

   use IO::Socket::SSL;
   my $imap = Mail::IMAPClient->new
    ( User     => 'your-username',
      Password => 'your-password',
      Socket   => IO::Socket::SSL->new
      (  Proto    => 'tcp',
         PeerAddr => 'some.imap.server',
         PeerPort => 993, # IMAP over SSL standard port
      ),
   );

If you need more control over the socket, e.g. you have to implement a
fancier authentication method, see L</RawSocket>.

=head2 Starttls

If an IMAP connection must start TLS/SSL after connecting to a server
then set this attribute.  If the value is set to an arrayref then they
will be used as arguments to IO::Socket::SSL->start_SSL.  By default
this connection is set to blocking while establishing the connection
with a timeout of 30 seconds.  The socket will be reset to the
original blocking/non-blocking value after a successful TLS
negotiation has occurred.  The arguments used in the call to start_SSL
can be controlled by setting this attribute to an ARRAY reference
containing the desired arguments.

Version note: attribute added in Mail::IMAPClient 3.22

=head2 Socketargs

The arguments used in the call to IO::Socket::{UNIX|INET|IP|SSL}->new
can be controlled by setting this attribute to an ARRAY reference
containing the desired arguments.

For example, to always pass MultiHomed => 1 to IO::Socket::...->new
the following can be used:

  $imap = Mail::IMAPClient->new(
    ..., Socketargs => [ MultiHomed => 1 ], ...
  );

See also L</Ssl> for specific control of the args to IO::Socket::SSL.

Version note: attribute added in Mail::IMAPClient 3.34

=head2 Ssl

If an IMAP connection requires SSL you can set the Ssl attribute to
'1' and Mail::IMAPClient will automatically use L<IO::Socket::SSL>
instead of IO::Socket::(INET|IP) to connect to the server.  This
attribute is used in the L</connect> method.  The arguments used in
the call to IO::Socket::SSL->new can be controlled by setting this
attribute to an ARRAY reference containing the desired arguments.

See also L</connect> for details on connection initiation and
L</Socket> and L</Rawsocket> if you need to take more control of
connection management.

Version note: attribute added in Mail::IMAPClient 3.18

=head2 Supportedflags

Especially when C<migrate()> is used, the receiving peer may need to
be configured explicitly with the list of supported flags; that may
be different from the source IMAP server.

The names are to be specified as an ARRAY.  Black-slashes and casing
will be ignored.

You may also specify a CODE reference, which will be called for each
of the flags separately.  In this case, the flags are not (yet)
normalized.  The returned lists of the CODE calls are shape the
resulting flag list.

=head2 Timeout

Example:

  $Timeout = $imap->Timeout();
  # or:
  $imap->Timeout($seconds);

Specifies the timeout value in seconds for reads (default is 600).
Specifying a I<Timeout> will prevent Mail::IMAPClient from blocking
in a read.

Since timeouts are implemented via the Perl L<select|perlfunc/select>
operator, the I<Timeout> parameter may be set to a fractional number
of seconds.  Setting I<Timeout> to 0 (zero) disables the timeout
feature.

=head2 Uid

Example:

  $Uid = $imap->Uid();
  # or:
  $imap->Uid($true_or_false);

If L</Uid> is set to a true value (i.e. 1) then the behavior of the
L</fetch>, L</search>, L</copy>, and L</store> methods (and their
derivatives) is changed so that arguments that would otherwise be
message sequence numbers are treated as message UID's and so that
return values (in the case of the L</search> method and its
derivatives) that would normally be message sequence numbers are
instead message UID's.

Internally this is implemented as a switch that, if turned on, causes
methods that would otherwise issue an IMAP FETCH, STORE, SEARCH, or
COPY client command to instead issue UID FETCH, UID STORE, UID SEARCH,
or UID COPY, respectively.  The main difference between message
sequence numbers and message UID's is that, according to RFC3501,
UID's must not change during a session and should not change between
sessions, and must never be reused.  Sequence numbers do not have that
same guarantee and in fact may be reused right away.

Since folder names also have a unique identifier (UIDVALIDITY), which
is provided when the folder is L</select>ed or L</examine>d or by
doing something like "$imap->status($folder,"UIDVALIDITY"), it is
possible to uniquely identify every message on the server, although
normally you won't need to bother.

The methods currently affected by turning on the L</Uid> flag are:

  copy            fetch
  search          store
  message_string  message_uid
  body_string     flags
  move            size
  parse_headers   thread

Note that if for some reason you only want the L</Uid> parameter turned
on for one command, then you can choose between the following two
snippets, which are equivalent:

Example 1:

  $imap->Uid(1);
  my @uids = $imap->search('SUBJECT',"Just a silly test"); #
  $imap->Uid(0);

Example 2:

  my @uids;
  foreach $r ($imap->UID("SEARCH","SUBJECT","Just a silly test") {
      chomp $r;
      $r =~ s/\r$//;
      $r =~ s/^\*\s+SEARCH\s+// or next;
      push @uids, grep(/\d/,(split(/\s+/,$r)));
  }

In the second example, we used the default method to issue the UID
IMAP Client command, being careful to use an all-uppercase method name
so as not to inadvertently call the L</Uid> accessor method.  Then we
parsed out the message UIDs manually, since we don't have the benefit
of the built-in L</search> method doing it for us.

Please be very careful when turning the L</Uid> parameter on and off
throughout a script.  If you loose track of whether you've got the
L</Uid> parameter turned on you might do something sad, like deleting
the wrong message.  Remember, like all eponymous accessor methods, the
B<Uid> method without arguments will return the current value for the
L</Uid> parameter, so do yourself a favor and check.  The safest
approach is probably to turn it on at the beginning (or just let it
default to being on) and then leave it on.  (Remember that leaving it
turned off can lead to problems if changes to a folder's contents
cause resequencing.)

By default, the L</Uid> parameter is turned on.

=head2 User

Example:

  $User = $imap->User();
  # or:
  $imap->User($userid);

Specifies the userid to use when logging into the IMAP service.  Can
be supplied with the L</new> method call or separately by calling the
B<User> object method.

Parameters can be set during L</new> method invocation by passing named
parameter/value pairs to the method, or later by calling the
parameter's eponymous object method.

=head1 Status Methods

There are several object methods that return the status of the object.
They can be used at any time to check the status of an IMAPClient
object, but are particularly useful for determining the cause of
failure when a connection and login are attempted as part of a single
L</new> method invocation.  The status methods are:

=head2 Escaped_history

Example:

  my @history = $imap->Escaped_history;

The B<Escaped_history> method is almost identical to the B<History>
method.  Unlike the B<History> method, however, server output
transmitted literally will be wrapped in double quotes, with all
double quotes, backslashes escaped.  If called in a scalar context,
B<Escaped_history> returns an array reference rather than an array.

B<Escaped_history> is useful if you are retrieving output and
processing it manually, and you are depending on the above special
characters to delimit the data.  It is not useful when retrieving
message contents; use B<message_string> or B<body_string> for that.

=head2 Escaped_results

Example:

  my @results = $imap->Escaped_results;

The B<Escaped_results> method is almost identical to the B<Results>
method.  Unlike the B<Results> method, however, server output
transmitted literally will be wrapped in double quotes, with all
double quotes, backslashes escaped.  If called in a scalar context,
B<Escaped_results> returns an array reference rather than an array.

B<Escaped_results> is useful if you are retrieving output and
processing it manually, and you are depending on the above special
characters to delimit the data.  It is not useful when retrieving
message contents; use B<message_string> or B<body_string> for that.

=head2 History

Example:

  my @history = $imap->History;

The B<History> method is almost identical to the L</Results> method.
Unlike the L</Results> method, however, the IMAP command that was
issued to create the results being returned is not included in the
returned results.  If called in a scalar context, B<History> returns
an array reference rather than an array.

=head2 IsUnconnected

returns a true value if the object is currently in an L</Unconnected>
state.

=head2 IsConnected

returns a true value if the object is currently in either a
L</Connected>, L</Authenticated>, or L</Selected> state.

=head2 IsAuthenticated

returns a true value if the object is currently in either an
L</Authenticated> or L</Selected> state.

=head2 IsSelected

returns a true value if the object is currently in a L</Selected>
state.

=head2 LastError

Internally B<LastError> is implemented just like a parameter (as
described in L</"Parameters">, above).  There is a I<LastError>
attribute and an eponymous accessor method which returns the
I<LastError> text string describing the last error condition
encountered by the server.

Note that some errors are more serious than others, so I<LastError>'s
value is only meaningful if you encounter an error condition that you
don't like.  For example, if you use the L</exists> method to see if a
folder exists and the folder does not exist, then an error message
will be recorded in I<LastError> even though this is not a
particularly serious error.  On the other hand, if you didn't use
L</exists> and just tried to L</select> a non-existing folder, then
L</select> would return C<undef> after setting I<LastError> to
something like C<NO SELECT failed: Can't open mailbox "mailbox": no
such mailbox>.  At this point it would be useful to print out the
contents of I<LastError> as you L<die|perlfunc/die>.

=head2 LastIMAPCommand

New in version 2.0.4, B<LastIMAPCommand> returns the exact IMAP
command string to be sent to the server.  Useful mainly in
constructing error messages when L</LastError> just isn't enough.

=head2 Report

The B<Report> method returns an array containing a history of the IMAP
session up to the point that B<Report> was called.  It is primarily
meant to assist in debugging but can also be used to retrieve raw
output for manual parsing.  The value of the L</Clear> parameter
controls how many transactions are in the report.

=head2 Results

The B<Results> method returns an array containing the results of one
IMAP client command.  It accepts one argument, the transaction number
of the command whose results are to be returned.  If transaction
number is unspecified then B<Results> returns the results of the last
IMAP client command issued.  If called in a scalar context, B<Results>
returns an array reference rather than an array.

=head2 State

The B<State> method returns a numerical value that indicates the
current status of the IMAPClient object.  If invoked with an argument,
it will set the object's state to that value.  If invoked without an
argument, it behaves just like L</Status>, below.

Normally you will not have to invoke this function.  An exception is
if you are bypassing the Mail::IMAPClient module's L</connect> and/or
L</login> modules to set up your own connection (say, for example,
over a secure socket), in which case you must manually do what the
L</connect> and L</login> methods would otherwise do for you.

=head2 Status

The B<Status> method returns a numerical value that indicates the
current status of the IMAPClient object.  (Not to be confused with the
L</status> method, all lower-case, which is the implementation of the
I<STATUS> IMAP client command.)

=head2 Transaction

The B<Transaction> method returns the tag value (or transaction
number) of the last IMAP client command.

=head1 Custom Authentication Mechanisms

If you just want to use plain text authentication or any of the
supported L</"Advanced Authentication Mechanisms"> then there is no
need to read this section.

There are a number of methods and parameters that you can use to build
your own authentication mechanism.  All of the methods and parameters
discussed in this section are described in more detail elsewhere in
this document.  This section provides a starting point for building
your own authentication mechanism.

There are I<many> authentication mechanisms out there, if your
preferred mechanism is not currently supported but you manage to get
it working please consider donating them to this module.  Patches and
suggestions are always welcome.

Support for add-on authentication mechanisms in Mail::IMAPClient is
pretty straight forward.  You create a callback to be used to provide
the response to the server's challenge.  The L</Authcallback> parameter
contains a reference to the callback, which can be an anonymous
subroutine or a named subroutine.  Then, you identify your
authentication mechanism, either via the L</Authmechanism> parameter or
as an argument to L</authenticate>.

You may also need to provide a subroutine to encrypt (or whatever)
data before it is sent to the server.  The L</Prewritemethod> parameter
must contain a reference to this subroutine.  And, you will need to
decrypt data from the server; a reference to the subroutine that does
this must be stored in the L</Readmethod> parameter.

This framework is based on the assumptions that a) the mechanism you
are using requires a challenge-response exchange, and b) the mechanism
does not fundamentally alter the exchange between client and server
but merely wraps the exchange in a layer of encryption.  It also
assumes that the line-oriented nature of the IMAP conversation is
preserved; authentication mechanisms that break up messages into
blocks of a predetermined size may still be possible but will
certainly be more difficult to implement.

Alternatively, if you have access to B<imtest>, a utility included in
the Cyrus IMAP distribution, you can use that utility to broker your
communications with the IMAP server.  This is quite easy to implement.
An example, F<examples/imtestExample.pl>, can be found in the
C<examples> subdirectory of the source distribution.

The following list summarizes the methods and parameters that you may
find useful in implementing advanced authentication:

=over 4

=item The authenticate method

The L</authenticate> method uses the L</Authmechanism> parameter to
determine how to authenticate with the server see the method
documentation for details.

=item Socket and RawSocket

The L</Socket> and L</RawSocket> methods provide access to the socket
connection.  The socket is typically automatically created by the
L</connect> method, but if you are implementing an advanced
authentication technique you may choose to set up your own socket
connection and then set this parameter manually, bypassing the
B<connect> method completely.  This is also useful if you want to use
IO::Socket::(INET|IP) alternatives like IO::Socket::SSL and need full
control.

L</RawSocket> simply gets/sets the socket without attempting any
interaction on it.  In this case, you have to be sure to handle all
the preliminary operations and manually set the Mail::IMAPClient
object in sync with its actual status with respect to this socket (see
below for additional parameters regarding this, especially the
L</State> parameter).

Unlike L</RawSocket>, L</Socket> attempts to carry on preliminary
connection phases if the conditions apply.  If both parameters are
present, this takes the precedence over L</RawSocket>.  If
L</Starttls> is set, then the L</starttls> method will be called by
L</Socket>.

B<PLEASE NOTE> As of version 2.99_04 of this module, semantics for
L</Socket> have changed to make it more "DWIM".  L</RawSocket> was
introduced as a replacement for the L</Socket> parameter in older
version.

=item State, Server, User, Password, Proxy and Domain Parameters

If you need to make your own connection to the server and perform your
authentication manually, then you can set these parameters to keep
your Mail::IMAPClient object in sync with its actual status.  Of
these, only the L</State> parameter is always necessary.  The others
need to be set only if you think your program will need them later.

=item Authmechanism

Set this to the value that AUTHENTICATE should send to the server as
the authentication mechanism.  If you are brokering your own
authentication then this parameter may be less useful.  It exists
primarily so that you can set it when you call L</new> to instantiate
your object.  The L</new> method will call L</connect>, which will
call L</login>.  If L</login> sees that you have set an
B<Authmechanism> then it will call B<authenticate>, using your
B<Authmechanism> and B<Authcallback> parameters as arguments.

=item Authcallback

The L</Authcallback>, if set, holds a pointer to a subroutine
(CODEREF).  The L</login> method will use this as the callback
argument to the B<authenticate> method if the B<Authmechanism> and
B<Authcallback> parameters are both set.  If you set B<Authmechanism>
but not B<Authcallback> then the default callback for your mechanism
will be used.  All supported authentication mechanisms have a default
callback; in every other case not supplying the callback results in an
error.

Most advanced authentication mechanisms require a challenge-response
exchange.  After the L</authenticate> method sends "<tag> AUTHENTICATE
<Authmechanism>\015\012" to the IMAP server, the server replies with a
challenge.  The L</authenticate> method then invokes the code whose
reference is stored in the B<Authcallback> parameter as follows:

  $Authcallback->( $challenge, $imap )

where C<$Authcallback> is the code reference stored in the
B<Authcallback> parameter, C<$challenge> is the challenge received
from the IMAP server, and C<$imap> is a pointer to the
Mail::IMAPClient object.  The return value from the B<Authcallback>
routine should be the response to the challenge, and that return value
will be sent by the L</authenticate> method to the server.

=item Prewritemethod/Readmethod

The B<Prewritemethod> can hold a subroutine that will do whatever
encryption is necessary and then return the result to the caller so it
in turn can be sent to the server.

The B<Readmethod> can hold a subroutine to be used to replace
B<sysread> usually performed by Mail::IMAPClient.

See L</Prewritemethod> and L</Readmethod> for details.

=back

=head1 REPORTING BUGS

Please send bug reports to C<bug-Mail-IMAPClient@rt.cpan.org> or
http://rt.cpan.org/Public/Dist/Display.html?Name=Mail-IMAPClient

=head1 COPYRIGHT AND LICENSE

  Copyright (C) 1999-2003 The Kernen Group, Inc.
  Copyright (C) 2007-2009 Mark Overmeer
  Copyright (C) 2010-2017 Phil Pearl (Lobbes)
  All rights reserved.

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself, either Perl version 5.8.0 or,
at your option, any later version of Perl 5 you may have available.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See either the
GNU General Public License or the Artistic License for more details.
