Chapter 2. Getting Started
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# Chapter 2. Getting Started

This section is intended as a brief overview of how to use Mutt. There are many other features which are described elsewhere in the manual. There is even more information available in the Mutt FAQ and various web pages. See the Mutt homepage for more details.

The keybindings described in this section are the defaults as distributed. Your local system administrator may have altered the defaults for your site. You can always type “?” in any menu to display the current bindings.

The first thing you need to do is invoke Mutt, simply by typing `mutt` at the command line. There are various command-line options, see either the Mutt man page or the reference.

## 1. Core Concepts

Mutt is a text-based application which interacts with users through different menus which are mostly line-/entry-based or page-based. A line-based menu is the so-called “index” menu (listing all messages of the currently opened folder) or the “alias” menu (allowing you to select recipients from a list). Examples for page-based menus are the “pager” (showing one message at a time) or the “help” menu listing all available key bindings.

The user interface consists of a context sensitive help line at the top, the menu's contents followed by a context sensitive status line and finally the command line. The command line is used to display informational and error messages as well as for prompts and for entering interactive commands.

Mutt is configured through variables which, if the user wants to permanently use a non-default value, are written to configuration files. Mutt supports a rich config file syntax to make even complex configuration files readable and commentable.

Because Mutt allows for customizing almost all key bindings, there are so-called “functions” which can be executed manually (using the command line) or in macros. Macros allow the user to bind a sequence of commands to a single key or a short key sequence instead of repeating a sequence of actions over and over.

Many commands (such as saving or copying a message to another folder) can be applied to a single message or a set of messages (so-called “tagged” messages). To help selecting messages, Mutt provides a rich set of message patterns (such as recipients, sender, body contents, date sent/received, etc.) which can be combined into complex expressions using the boolean and and or operations as well as negating. These patterns can also be used to (for example) search for messages or to limit the index to show only matching messages.

Mutt supports a “hook” concept which allows the user to execute arbitrary configuration commands and functions in certain situations such as entering a folder, starting a new message or replying to an existing one. These hooks can be used to highly customize Mutt's behavior including managing multiple identities, customizing the display for a folder or even implementing auto-archiving based on a per-folder basis and much more.

Besides an interactive mode, Mutt can also be used as a command-line tool to send messages. It also supports a `mailx(1)`-compatible interface, see Table 9.1, “Command line options” for a complete list of command-line options.

## 2. Screens and Menus

### 2.1. Index

The index is the screen that you usually see first when you start Mutt. It gives an overview over your emails in the currently opened mailbox. By default, this is your system mailbox. The information you see in the index is a list of emails, each with its number on the left, its flags (new email, important email, email that has been forwarded or replied to, tagged email, ...), the date when email was sent, its sender, the email size, and the subject. Additionally, the index also shows thread hierarchies: when you reply to an email, and the other person replies back, you can see the other person's email in a "sub-tree" below. This is especially useful for personal email between a group of people or when you've subscribed to mailing lists.

### 2.2. Pager

The pager is responsible for showing the email content. On the top of the pager you have an overview over the most important email headers like the sender, the recipient, the subject, and much more information. How much information you actually see depends on your configuration, which we'll describe below.

Below the headers, you see the email body which usually contains the message. If the email contains any attachments, you will see more information about them below the email body, or, if the attachments are text files, you can view them directly in the pager.

To give the user a good overview, it is possible to configure Mutt to show different things in the pager with different colors. Virtually everything that can be described with a regular expression can be colored, e.g. URLs, email addresses or smileys.

### 2.3. File Browser

The file browser is the interface to the local or remote file system. When selecting a mailbox to open, the browser allows custom sorting of items, limiting the items shown by a regular expression and a freely adjustable format of what to display in which way. It also allows for easy navigation through the file system when selecting file(s) to attach to a message, select multiple files to attach and many more.

Some mail systems can nest mail folders inside other mail folders. The normal open entry commands in mutt will open the mail folder and you can't see the sub-folders. If you instead use the `<descend-directory>` function it will go into the directory and not open it as a mail directory.

### 2.4. Sidebar

The Sidebar shows a list of all your mailboxes. The list can be turned on and off, it can be themed and the list style can be configured.

### 2.5. Help

The help screen is meant to offer a quick help to the user. It lists the current configuration of key bindings and their associated commands including a short description, and currently unbound functions that still need to be associated with a key binding (or alternatively, they can be called via the Mutt command prompt).

### 2.6. Compose Menu

The compose menu features a split screen containing the information which really matter before actually sending a message by mail: who gets the message as what (recipients and who gets what kind of copy). Additionally, users may set security options like deciding whether to sign, encrypt or sign and encrypt a message with/for what keys. Also, it's used to attach messages, to re-edit any attachment including the message itself.

### 2.7. Alias Menu

The alias menu is used to help users finding the recipients of messages. For users who need to contact many people, there's no need to remember addresses or names completely because it allows for searching, too. The alias mechanism and thus the alias menu also features grouping several addresses by a shorter nickname, the actual alias, so that users don't have to select each single recipient manually.

### 2.8. Attachment Menu

As will be later discussed in detail, Mutt features a good and stable MIME implementation, that is, it supports sending and receiving messages of arbitrary MIME types. The attachment menu displays a message's structure in detail: what content parts are attached to which parent part (which gives a true tree structure), which type is of what type and what size. Single parts may saved, deleted or modified to offer great and easy access to message's internals.

## 3. Moving Around in Menus

The most important navigation keys common to line- or entry-based menus are shown in Table 2.1, “Most common navigation keys in entry-based menus” and in Table 2.2, “Most common navigation keys in page-based menus” for page-based menus.

Table 2.1. Most common navigation keys in entry-based menus

Key | Function | Description
--- | --- | ---
j or <Down> | `<next-entry>` | move to the next entry
k or <Up> | `<previous-entry>` | move to the previous entry
z or <PageDn> | `<page-down>` | go to the next page
Z or <PageUp> | `<page-up>` | go to the previous page
= or <Home> | `<first-entry>` | jump to the first entry
* or <End> | `<last-entry>` | jump to the last entry
q | `<quit>` | exit the current menu
? | `<help>` | list all keybindings for the current menu

Table 2.2. Most common navigation keys in page-based menus

Key | Function | Description
--- | --- | ---
J or <Return> | `<next-line>` | scroll down one line
<Backspace> | `<previous-line>` | scroll up one line
K, <Space> or <PageDn> | `<next-page>` | move to the next page
- or <PageUp> | `<previous-page>` | move the previous page
<Home> | `<top>` | move to the top
<End> | `<bottom>` | move to the bottom

## 4. Editing Input Fields

### 4.1. Introduction

Mutt has a built-in line editor for inputting text, e.g. email addresses or filenames. The keys used to manipulate text input are very similar to those of Emacs. See Table 2.3, “Most common line editor keys” for a full reference of available functions, their default key bindings, and short descriptions.

Table 2.3. Most common line editor keys

Key | Function | Description
--- | --- | ---
^A or <Home> | `<bol>` | move to the start of the line
^B or <Left> | `<backward-char>` | move back one char
Esc B | `<backward-word>` | move back one word
^D or <Delete> | `<delete-char>` | delete the char under the cursor
^E or <End> | `<eol>` | move to the end of the line
^F or <Right> | `<forward-char>` | move forward one char
Esc F | `<forward-word>` | move forward one word
<Tab> | `<complete>` | complete filename, alias, or label
^T | `<complete-query>` | complete address with query
^K | `<kill-eol>` | delete to the end of the line
Esc d | `<kill-eow>` | delete to the end of the word
^W | `<kill-word>` | kill the word in front of the cursor
^U | `<kill-line>` | delete entire line
^V | `<quote-char>` | quote the next typed key
<Up> | `<history-up>` | recall previous string from history
<Down> | `<history-down>` | recall next string from history
^R | `<history-search>` | use current input to search history
<BackSpace> | `<backspace>` | kill the char in front of the cursor
Esc u | `<upcase-word>` | convert word to upper case
Esc l | `<downcase-word>` | convert word to lower case
Esc c | `<capitalize-word>` | capitalize the word
^G | n/a | abort
<Return> | n/a | finish editing

You can remap the editor functions using the bind command. For example, to make the <Delete> key delete the character in front of the cursor rather than under, you could use:

    bind editor <delete> backspace

### 4.2. History

Mutt maintains a history for the built-in editor. The number of items is controlled by the $history variable and can be made persistent using an external file specified using $history_file and $save_history. You may cycle through them at an editor prompt by using the `<history-up>` and/or `<history-down>` commands. Mutt will remember the currently entered text as you cycle through history, and will wrap around to the initial entry line.

Mutt maintains several distinct history lists, one for each of the following categories:

- `.muttrc` commands

- addresses and aliases

- shell commands

- filenames

- patterns

- everything else

Mutt automatically filters out consecutively repeated items from the history. If $history_remove_dups is set, all repeated items are removed from the history. It also mimics the behavior of some shells by ignoring items starting with a space. The latter feature can be useful in macros to not clobber the history's valuable entries with unwanted entries.

## 5. Reading Mail

Similar to many other mail clients, there are two modes in which mail is read in Mutt. The first is a list of messages in the mailbox, which is called the “index” menu in Mutt. The second mode is the display of the message contents. This is called the “pager.”

The next few sections describe the functions provided in each of these modes.

### 5.1. The Message Index

Common keys used to navigate through and manage messages in the index are shown in Table 2.4, “Most common message index keys”. How messages are presented in the index menu can be customized using the $index_format variable.

Table 2.4. Most common message index keys

Key | Description
--- | ---
c | change to a different mailbox
Esc c | change to a folder in read-only mode
C | copy the current message to another mailbox
Esc C | decode a message and copy it to a folder
Esc s | decode a message and save it to a folder
D | delete messages matching a pattern
d | delete the current message
F | mark as important
l | show messages matching a pattern
N | mark message as new
o | change the current sort method
O | reverse sort the mailbox
q | save changes and exit
s | save-message
T | tag messages matching a pattern
t | toggle the tag on a message
Esc t | toggle tag on entire message thread
U | undelete messages matching a pattern
u | undelete-message
v | view-attachments
x | abort changes and exit
<Return> | display-message
<Tab> | jump to the next new or unread message
@ | show the author's full e-mail address
$ | save changes to mailbox
/ | search
Esc / | search-reverse
^L | clear and redraw the screen
^T | untag messages matching a pattern

In addition to who sent the message and the subject, a short summary of the disposition of each message is printed beside the message number. Zero or more of the “flags” in Table 2.5, “Message status flags” may appear, some of which can be turned on or off using these functions: `<set-flag>` and `<clear-flag>` bound by default to “w” and “W” respectively.

Furthermore, the flags in Table 2.6, “Message recipient flags” reflect who the message is addressed to. They can be customized with the $to_chars variable.

Table 2.5. Message status flags

Flag | Description
--- | ---
D | message is deleted (is marked for deletion)
d | message has attachments marked for deletion
K | contains a PGP public key
N | message is new
O | message is old
P | message is PGP encrypted
r | message has been replied to
S | message is signed, and the signature is successfully verified
s | message is signed
! | message is flagged
* | message is tagged
n | thread contains new messages (only if collapsed)
o | thread contains old messages (only if collapsed)

Table 2.6. Message recipient flags

Flag | Description
--- | ---
+ | message is to you and you only
T | message is to you, but also to or CC'ed to others
C | message is CC'ed to you
F | message is from you
L | message is sent to a subscribed mailing list

### 5.2. The Pager

By default, Mutt uses its built-in pager to display the contents of messages (an external pager such as `less(1)` can be configured, see $pager variable). The pager is very similar to the Unix program `less(1)` though not nearly as featureful.

Table 2.7. Most common pager keys

Key | Description
--- | ---
<Return> | go down one line
<Space> | display the next page (or next message if at the end of a message)
- | go back to the previous page
n | search for next match
S | skip beyond quoted text
T | toggle display of quoted text
? | show keybindings
/ | regular expression search
Esc / | backward regular expression search
\ | toggle highlighting of search matches
^ | jump to the top of the message

In addition to key bindings in Table 2.7, “Most common pager keys”, many of the functions from the index menu are also available in the pager, such as `<delete-message>` or `<copy-message>` (this is one advantage over using an external pager to view messages).

Also, the internal pager supports a couple other advanced features. For one, it will accept and translate the “standard” nroff sequences for bold and underline. These sequences are a series of either the letter, backspace (“^H”), the letter again for bold or the letter, backspace, “_” for denoting underline. Mutt will attempt to display these in bold and underline respectively if your terminal supports them. If not, you can use the bold and underline color objects to specify a color or mono attribute for them.

Additionally, the internal pager supports the ANSI escape sequences for character attributes. Mutt translates them into the correct color and character settings. The sequences Mutt supports are:

    \e[Ps;Ps;..Ps;m

where Ps can be one of the codes shown in Table 2.8, “ANSI escape sequences”.

Table 2.8. ANSI escape sequences

Escape code | Description
--- | ---
0 | All attributes off
1 | Bold on
4 | Underline on
5 | Blink on
7 | Reverse video on
3<color> | Foreground color is <color> (see Table 2.9, “Color sequences”)
4<color> | Background color is <color> (see Table 2.9, “Color sequences”)

Table 2.9. Color sequences

Color code | Color
--- | ---
0 | Black
1 | Red
2 | Green
3 | Yellow
4 | Blue
5 | Magenta
6 | Cyan
7 | White

Mutt uses these attributes for handling `text/enriched` messages, and they can also be used by an external autoview script for highlighting purposes.

### Note

If you change the colors for your display, for example by changing the color associated with color2 for your xterm, then that color will be used instead of green.

### Note

Note that the search commands in the pager take regular expressions, which are not quite the same as the more complex patterns used by the search command in the index. This is because patterns are used to select messages by criteria whereas the pager already displays a selected message.

### 5.3. Threaded Mode

So-called “threads” provide a hierarchy of messages where replies are linked to their parent message(s). This organizational form is extremely useful in mailing lists where different parts of the discussion diverge. Mutt displays threads as a tree structure.

In Mutt, when a mailbox is sorted by threads, there are a few additional functions available in the index and pager modes as shown in Table 2.10, “Most common thread mode keys”.

Table 2.10. Most common thread mode keys

Key | Function | Description
--- | --- | ---
^D | `<delete-thread>` | delete all messages in the current thread
^U | `<undelete-thread>` | undelete all messages in the current thread
^N | `<next-thread>` | jump to the start of the next thread
^P | `<previous-thread>` | jump to the start of the previous thread
^R | `<read-thread>` | mark the current thread as read
Esc d | `<delete-subthread>` | delete all messages in the current subthread
Esc u | `<undelete-subthread>` | undelete all messages in the current subthread
Esc n | `<next-subthread>` | jump to the start of the next subthread
Esc p | `<previous-subthread>` | jump to the start of the previous subthread
Esc r | `<read-subthread>` | mark the current subthread as read
Esc t | `<tag-thread>` | toggle the tag on the current thread
Esc v | `<collapse-thread>` | toggle collapse for the current thread
Esc V | `<collapse-all>` | toggle collapse for all threads
P | `<parent-message>` | jump to parent message in thread

In the index, the subject of threaded children messages will be prepended with thread tree characters. By default, the subject itself will not be duplicated unless $hide_thread_subject is unset. Special characters will be added to the thread tree as detailed in Table 2.11, “Special Thread Characters”.

Table 2.11. Special Thread Characters

Character | Description | Notes
--- | --- | ---
& | hidden message | see $hide_limited and $hide_top_limited
? | missing message | see $hide_missing and $hide_top_missing
* | pseudo thread | see $strict_threads; not displayed when $narrow_tree is set
= | duplicate thread | see $duplicate_threads; not displayed when $narrow_tree is set

Collapsing a thread displays only the first message in the thread and hides the others. This is useful when threads contain so many messages that you can only see a handful of threads on the screen. See %M in $index_format. For example, you could use “%?M?(#%03M)&(%4l)?” in $index_format to optionally display the number of hidden messages if the thread is collapsed. The `%?<char>?<if-part>&<else-part>?` syntax is explained in detail in format string conditionals.

Technically, every reply should contain a list of its parent messages in the thread tree, but not all do. In these cases, Mutt groups them by subject which can be controlled using the $strict_threads variable.

### 5.4. Miscellaneous Functions

In addition, the index and pager menus have these interesting functions:

`<check-stats>`

  Calculate statistics for all monitored mailboxes declared using the mailboxes command. It will calculate statistics despite $mail_check_stats being unset.

`<create-alias>` (default: a)

  Creates a new alias based upon the current message (or prompts for a new one). Once editing is complete, an alias command is added to the file specified by the $alias_file variable for future use

  ### Note

  Mutt does not read the $alias_file upon startup so you must explicitly source the file.

`<check-traditional-pgp>` (default: Esc P)

  This function will search the current message for content signed or encrypted with PGP the “traditional” way, that is, without proper MIME tagging. Technically, this function will temporarily change the MIME content types of the body parts containing PGP data; this is similar to the `<edit-type>` function's effect.

`<edit>` (default: e)

  This command (available in the index and pager) allows you to edit the raw current message as it's present in the mail folder. After you have finished editing, the changed message will be appended to the current folder, and the original message will be marked for deletion; if the message is unchanged it won't be replaced.

`<edit-type>` (default: ^E on the attachment menu, and in the pager and index menus; ^T on the compose menu)

  This command is used to temporarily edit an attachment's content type to fix, for instance, bogus character set parameters. When invoked from the index or from the pager, you'll have the opportunity to edit the top-level attachment's content type. On the attachment menu, you can change any attachment's content type. These changes are not persistent, and get lost upon changing folders.

  Note that this command is also available on the compose menu. There, it's used to fine-tune the properties of attachments you are going to send.

`<enter-command>` (default: “:”)

  This command is used to execute any command you would normally put in a configuration file. A common use is to check the settings of variables, or in conjunction with macros to change settings on the fly.

`<extract-keys>` (default: ^K)

  This command extracts PGP public keys from the current or tagged message(s) and adds them to your PGP public key ring.

`<forget-passphrase>` (default: ^F)

  This command wipes the passphrase(s) from memory. It is useful, if you misspelled the passphrase.

`<list-reply>` (default: L)

  Reply to the current or tagged message(s) by extracting any addresses which match the regular expressions given by the lists or subscribe commands, but also honor any `Mail-Followup-To` header(s) if the $honor_followup_to configuration variable is set. In addition, the `List-Post` header field is examined for `mailto:` URLs specifying a mailing list address. Using this when replying to messages posted to mailing lists helps avoid duplicate copies being sent to the author of the message you are replying to.

`<pipe-message>` (default: |)

  Asks for an external Unix command and pipes the current or tagged message(s) to it. The variables $pipe_decode, $pipe_split, $pipe_sep and $wait_key control the exact behavior of this function.

`<resend-message>` (default: Esc e)

  Mutt takes the current message as a template for a new message. This function is best described as "recall from arbitrary folders". It can conveniently be used to forward MIME messages while preserving the original mail structure. Note that the amount of headers included here depends on the value of the $weed variable.

  This function is also available from the attachment menu. You can use this to easily resend a message which was included with a bounce message as a `message/rfc822` body part.

`<shell-escape>` (default: !)

  Asks for an external Unix command and executes it. The $wait_key can be used to control whether Mutt will wait for a key to be pressed when the command returns (presumably to let the user read the output of the command), based on the return status of the named command. If no command is given, an interactive shell is executed.

`<toggle-quoted>` (default: T)

  The pager uses the $quote_regexp variable to detect quoted text when displaying the body of the message. This function toggles the display of the quoted material in the message. It is particularly useful when being interested in just the response and there is a large amount of quoted text in the way.

`<skip-quoted>` (default: S)

  This function will go to the next line of non-quoted text which comes after a line of quoted text in the internal pager.

## 6. Sending Mail

### 6.1. Introduction

The bindings shown in Table 2.12, “Most common mail sending keys” are available in the index and pager to start a new message.

Table 2.12. Most common mail sending keys

Key | Function | Description
--- | --- | ---
m | `<compose>` | compose a new message
r | `<reply>` | reply to sender
g | `<group-reply>` | reply to all recipients
| `<group-chat-reply>` | reply to all recipients preserving To/Cc
L | `<list-reply>` | reply to mailing list address
f | `<forward>` | forward message
b | `<bounce>` | bounce (remail) message
Esc k | `<mail-key>` | mail a PGP public key to someone

Bouncing a message sends the message as-is to the recipient you specify. Forwarding a message allows you to add comments or modify the message you are forwarding. These items are discussed in greater detail in the next section “Forwarding and Bouncing Mail.”

Mutt will then enter the compose menu and prompt you for the recipients to place on the “To:” header field when you hit `m` to start a new message. Next, it will ask you for the “Subject:” field for the message, providing a default if you are replying to or forwarding a message. You again have the chance to adjust recipients, subject, and security settings right before actually sending the message. See also $askcc, $askbcc, $autoedit, $bounce, $fast_reply, and $include for changing how and if Mutt asks these questions.

When replying, Mutt fills these fields with proper values depending on the reply type. The types of replying supported are:

Simple reply

  Reply to the author directly.

Group reply

  Reply to the author; cc all other recipients; consults alternates and excludes you.

Group Chat reply

  Reply to the author and other recipients in the To list; cc other recipients in the Cc list; consults alternates and excludes you.

List reply

  Reply to all mailing list addresses found, either specified via configuration or auto-detected. See Section 13, “Mailing Lists” for details.

After getting recipients for new messages, forwards or replies, Mutt will then automatically start your $editor on the message body. If the $edit_headers variable is set, the headers will be at the top of the message in your editor; the message body should start on a new line after the existing blank line at the end of headers. Any messages you are replying to will be added in sort order to the message, with appropriate $attribution, $indent_string and $post_indent_string. When forwarding a message, if the $mime_forward variable is unset, a copy of the forwarded message will be included. If you have specified a $signature, it will be appended to the message.

Once you have finished editing the body of your mail message, you are returned to the compose menu providing the functions shown in Table 2.13, “Most common compose menu keys” to modify, send or postpone the message.

Table 2.13. Most common compose menu keys

Key | Function | Description
--- | --- | ---
a | `<attach-file>` | attach a file
A | `<attach-message>` | attach message(s) to the message
Esc k | `<attach-key>` | attach a PGP public key
d | `<edit-description>` | edit description on attachment
D | `<detach-file>` | detach a file
t | `<edit-to>` | edit the To field
Esc f | `<edit-from>` | edit the From field
r | `<edit-reply-to>` | edit the Reply-To field
c | `<edit-cc>` | edit the Cc field
b | `<edit-bcc>` | edit the Bcc field
y | `<send-message>` | send the message
s | `<edit-subject>` | edit the Subject
S | `<smime-menu>` | select S/MIME options
f | `<edit-fcc>` | specify an “Fcc” mailbox
p | `<pgp-menu>` | select PGP options
P | `<postpone-message>` | postpone this message until later
q | `<quit>` | quit (abort) sending the message
w | `<write-fcc>` | write the message to a folder
i | `<ispell>` | check spelling (if available on your system)
^F | `<forget-passphrase>` | wipe passphrase(s) from memory

The compose menu is also used to edit the attachments for a message which can be either files or other messages. The `<attach-message>` function to will prompt you for a folder to attach messages from. You can now tag messages in that folder and they will be attached to the message you are sending.

### Note

Note that certain operations like composing a new mail, replying, forwarding, etc. are not permitted when you are in that folder. The %r in $status_format will change to a “A” to indicate that you are in attach-message mode.

After exiting the compose menu via `<send-message>`, the message will be sent. If configured and enabled, this can happen via mixmaster or $smtp_url. Otherwise $sendmail will be invoked. Prior to version 1.13, Mutt enabled $write_bcc by default, assuming the MTA would automatically remove a `Bcc:` header as part of delivery. Starting with 1.13, the option is unset by default, but no longer affects the fcc copy of the message.

### 6.2. Editing the Message Header

When editing the header because of $edit_headers being set, there are a several pseudo headers available which will not be included in sent messages but trigger special Mutt behavior.

#### 6.2.1. Fcc: Pseudo Header

If you specify

`Fcc:` filename

as a header, Mutt will pick up filename just as if you had used the `<edit-fcc>` function in the compose menu. It can later be changed from the compose menu.

#### 6.2.2. Attach: Pseudo Header

You can also attach files to your message by specifying

`Attach:` filename [ description ]

where filename is the file to attach and description is an optional string to use as the description of the attached file. Spaces in filenames have to be escaped using backslash (“\”). The file can be removed as well as more added from the compose menu.

#### 6.2.3. Pgp: Pseudo Header

If you want to use PGP, you can specify

`Pgp:` [ `E` | `S` | `S`<id> ]

“E” selects encryption, “S” selects signing and “S<id>” selects signing with the given key, setting $pgp_sign_as for the duration of the message composition session. The selection can later be changed in the compose menu.

#### 6.2.4. In-Reply-To: Header

When replying to messages, the In-Reply-To: header contains the Message-Id of the message(s) you reply to. If you remove or modify its value, Mutt will not generate a References: field, which allows you to create a new message thread, for example to create a new message to a mailing list without having to enter the mailing list's address.

If you intend to start a new thread by replying, please make really sure you remove the In-Reply-To: header in your editor. Otherwise, though you'll produce a technically valid reply, some netiquette guardians will be annoyed by this so-called “thread hijacking”.

### 6.3. Sending Cryptographically Signed/Encrypted Messages

If you have told Mutt to PGP or S/MIME encrypt a message, it will guide you through a key selection process when you try to send the message. Mutt will not ask you any questions about keys which have a certified user ID matching one of the message recipients' mail addresses. However, there may be situations in which there are several keys, weakly certified user ID fields, or where no matching keys can be found.

In these cases, you are dropped into a menu with a list of keys from which you can select one. When you quit this menu, or Mutt can't find any matching keys, you are prompted for a user ID. You can, as usually, abort this prompt using `^G`. When you do so, Mutt will return to the compose screen.

Once you have successfully finished the key selection, the message will be encrypted using the selected public keys when sent out.

To ensure you can view encrypted messages you have sent, you may wish to set $pgp_self_encrypt and $pgp_default_key for PGP, or $smime_self_encrypt and $smime_default_key for S/MIME.

Most fields of the entries in the key selection menu (see also $pgp_entry_format) have obvious meanings. But some explanations on the capabilities, flags, and validity fields are in order.

The flags sequence (“%f”) will expand to one of the flags in Table 2.14, “PGP key menu flags”.

Table 2.14. PGP key menu flags

Flag | Description
--- | ---
R | The key has been revoked and can't be used.
X | The key is expired and can't be used.
d | You have marked the key as disabled.
c | There are unknown critical self-signature packets.

The capabilities field (“%c”) expands to a two-character sequence representing a key's capabilities. The first character gives the key's encryption capabilities: A minus sign (“-”) means that the key cannot be used for encryption. A dot (“.”) means that it's marked as a signature key in one of the user IDs, but may also be used for encryption. The letter “e” indicates that this key can be used for encryption.

The second character indicates the key's signing capabilities. Once again, a “-” implies “not for signing”, “.” implies that the key is marked as an encryption key in one of the user-ids, and “s” denotes a key which can be used for signing.

Finally, the validity field (“%t”) indicates how well-certified a user-id is. A question mark (“?”) indicates undefined validity, a minus character (“-”) marks an untrusted association, a space character means a partially trusted association, and a plus character (“+”) indicates complete validity.

### 6.4. Sending Format=Flowed Messages

#### 6.4.1. Concept

`format=flowed`-style messages (or `f=f` for short) are `text/plain` messages that consist of paragraphs which a receiver's mail client may reformat to its own needs which mostly means to customize line lengths regardless of what the sender sent. Technically this is achieved by letting lines of a “flowable” paragraph end in spaces except for the last line.

While for text-mode clients like Mutt it's the best way to assume only a standard 80x25 character cell terminal, it may be desired to let the receiver decide completely how to view a message.

#### 6.4.2. Mutt Support

Mutt only supports setting the required `format=flowed` MIME parameter on outgoing messages if the $text_flowed variable is set, specifically it does not add the trailing spaces.

After editing, Mutt properly space-stuffs the message. Space-stuffing is required by RfC3676 defining `format=flowed` and means to prepend a space to:

- all lines starting with a space

- lines starting with the word “`From`” followed by space

- all lines starting with “`>`” which is not intended to be a quote character

### Note

Mutt only supports space-stuffing for the first two types of lines but not for the third: It is impossible to safely detect whether a leading `>` character starts a quote or not.

All leading spaces are to be removed by receiving clients to restore the original message prior to further processing.

#### 6.4.3. Editor Considerations

As Mutt provides no additional features to compose `f=f` messages, it's completely up to the user and his editor to produce proper messages. Please consider your editor's documentation if you intend to send `f=f` messages.

For example, vim provides the `w` flag for its `formatoptions` setting to assist in creating `f=f` messages, see `:help fo-table` for details.

#### 6.4.4. Reformatting

Mutt has some support for reformatting when viewing and replying to `format=flowed` messages. In order to take advantage of these, $reflow_text must be set.

- Paragraphs are automatically reflowed and wrapped at a width specified by $reflow_wrap.

- In its original format, the quoting style of `format=flowed` messages can be difficult to read, and doesn't intermix well with non-flowed replies. Setting $reflow_space_quotes adds spaces after each level of quoting when in the pager and replying in a non-flowed format (i.e. with $text_flowed unset).

- If $reflow_space_quotes is unset, mutt will still add one trailing space after all the quotes in the pager (but not when replying).

### 6.5. Background Editing

If $editor is set to a graphical editor, or a script such as contrib/bgedit-screen-tmux.sh if running inside GNU Screen or tmux, you can run the editor in the background by setting $background_edit.

If set, Mutt will display a landing page while the editor runs. When the editor exits, message composition will resume automatically. Alternatively, you can `<exit>` from the landing page, which will return you to the message index. This allows viewing other messages, changing mailboxes, even starting a new message composition session - all while the first editor session is still running.

Backgrounded message composition sessions can be viewed via `<background-compose-menu>` in the index and pager, by default bound to “`B`”. If there is only a single backgrounded session, which has already exited, that session will automatically resume. Otherwise the list will be displayed, and a particular session can be selected. $background_format controls the format string used for the menu.

In case the open mailbox is changed while a reply is backgrounded, Mutt keeps track of the original mailbox. After sending, Mutt will attempt to reopen the original mailbox, if needed, and set reply flags appropriately. This won't affect your currently open mailbox, but may make setting flags a bit slower due to the need to reopen the original mailbox behind the scenes.

One complication with backgrounded compose sessions is the config changes caused by send, reply, and folder hooks. These can get triggered by a new message composition session, or by changing folders during a backgrounded session. To help lessen these problems, Mutt takes a snapshot of certain configuration variables and stores them with each editing session when it is backgrounded. When the session is resumed, those stored settings will temporarily be restored, and removed again when the session finishes (or is backgrounded again).

Mutt will save all `boolean` and `quadoption` configuration variables, along with $folder, $record, $postponed, $envelope_from_address, $from, $sendmail, $smtp_url, $pgp_sign_as, $smime_sign_as, and $smime_encrypt_with. It's not feasible to backup all variables, but if you believe we've missed an important setting, please let the developers know.

To help prevent forgetting about backgrounded sessions, $background_confirm_quit will prompt before exiting, in addition to $quit. Additionally, the `%B` expando in $status_format displays the number of backgrounded compose sessions.

Background editing is available for most, but not all, message composition in Mutt. Sending from the command line disables background editing, because there is no index to return to.

## 7. Forwarding and Bouncing Mail

Bouncing and forwarding let you send an existing message to recipients that you specify. Bouncing a message sends a verbatim copy of a message to alternative addresses as if they were the message's original recipients specified in the Bcc header. Forwarding a message, on the other hand, allows you to modify the message before it is resent (for example, by adding your own comments). Bouncing is done using the `<bounce>` function and forwarding using the `<forward>` function bound to “b” and “f” respectively.

Forwarding can be done by including the original message in the new message's body (surrounded by indicating lines) or including it as a MIME attachment, depending on the value of the $mime_forward variable. Decoding of attachments, like in the pager, can be controlled by the $forward_decode and $mime_forward_decode variables, respectively. The desired forwarding format may depend on the content, therefore $mime_forward is a quadoption which, for example, can be set to “ask-no”.

Mutt's default ($mime_forward=“no” and $forward_decode=“yes”) is to use standard inline forwarding. In that mode all text-decodable parts are included in the new message body. Other attachments from the original email can also be attached to the new message, based on the quadoption $forward_attachments.

The inclusion of headers is controlled by the current setting of the $weed variable, unless $mime_forward is set.

Editing the message to forward follows the same procedure as sending or replying to a message does, but can be disabled via the quadoption $forward_edit.

## 8. Postponing Mail

At times it is desirable to delay sending a message that you have already begun to compose. When the `<postpone-message>` function is used in the compose menu, the body of your message and attachments are stored in the mailbox specified by the $postponed variable. This means that you can recall the message even if you exit Mutt and then restart it at a later time.

Once a message is postponed, there are several ways to resume it. From the command line you can use the “-p” option, or if you compose a new message from the index or pager you will be prompted if postponed messages exist. If multiple messages are currently postponed, the postponed menu will pop up and you can select which message you would like to resume.

### Note

If you postpone a reply to a message, the reply setting of the message is only updated when you actually finish the message and send it. Also, you must be in the same folder with the message you replied to for the status of the message to be updated.

See also the $postpone quad-option.

## 9. Encryption and Signing

OpenPGP and S/MIME are enabled in one of two ways: “classic mode” or GPGME. The former invokes external programs to perform the various operations; it is better tested and more flexible, but requires some configuration. The latter uses the GnuPG project's GPGME library.

To enable “classic mode”, ensure GPGME is disabled and use the `gpg.rc` or `smime.rc` files that come with mutt. These are typically installed under `/usr/local/share/doc/mutt/samples/`. Source them, either directly or by copying them to your .mutt directory and sourcing them. Sourcing them directly from `/usr/local/share/doc/mutt/samples/` has the benefit of automatically using fixes and security improvements to the command invocations, and is recommended.

    unset crypt_use_gpgme
    source /usr/local/share/doc/mutt/samples/gpg.rc
    source /usr/local/share/doc/mutt/samples/smime.rc

To use GPGME instead, simply ensure the option is enabled in your .muttrc:

    set crypt_use_gpgme

### 9.1. OpenPGP Configuration

The two most important settings are $pgp_default_key and $pgp_sign_as. To perform encryption, you must set the first variable. If you have a separate signing key, or only have a signing key, then set the second. Most people will only need to set $pgp_default_key.

Starting with version 2.1.0, GnuPG automatically uses an `agent` to prompt for your passphrase. If you are using a version older than that, you'll need to ensure an agent is running (alternatively, you can unset $pgp_use_gpg_agent and Mutt will prompt you for your passphrase). The agent in turn uses a `pinentry` program to display the prompt. There are many different kinds of pinentry programs that can be used: qt, gtk2, gnome3, fltk, and curses. However, Mutt does not work properly with the tty pinentry program. Please ensure you have one of the GUI or curses pinentry programs installed and configured to be the default for your system.

### 9.2. S/MIME Configuration

As with OpenPGP, the two most important settings are $smime_default_key and $smime_sign_as. To perform encryption and decryption, you must set the first variable. If you have a separate signing key, or only have a signing key, then set the second. Most people will only need to set $smime_default_key.

In “classic mode”, keys and certificates are managed by the `smime_keys` program that comes with Mutt. By default they are stored under `~/.smime/`. (This is set by the `smime.rc` file with $smime_certificates and $smime_keys.) To initialize this directory, use the command “`smime_keys init`” from a shell prompt. The program can be then be used to import and list certificates. You may also want to periodically run “`smime_keys refresh`” to update status flags for your certificates.

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