Supported Quota Types — Cyrus IMAP 3.0.9 (stable) documentation

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# Supported Quota Types

The Cyrus IMAP server supports quotas on Storage (KB), Messages (#), Folders (#) and Annotation Storage (KB). These types each have their own identifier:

> - STORAGE
> - MESSAGE
> - X-NUM-FOLDERS
> - X-ANNOTATION-STORAGE

## Storage Quotas

Storage quotas are defined as the number of kilobytes (KB) of the relevant RFC 822 messages located within a quota root. Each copy of a message is counted independently, even when the server can conserve disk space use by making hard links to message files. The additional disk space overhead used by mailbox index and cache files is not charged against a quota. On servers with `delete_mode: delayed` and/or `expunge_mode:delayed` space used by deleted mailboxes or expunged messages are not charged against quota.

## Numeric Quotas

Numeric Quotas are quite simply a limit on the number of a particular class of object. Cyrus IMAP currently supports quotas on the number of messages and/or folders below a given quota root.