Quotas
******

Cyrus IMAP features a flexible Quota scheme with support for limiting
various resources, such as storage or number of folders or messages.

* Quota Roots

* Supported Quota Types


Monitor and Repair
==================

Quotas may be monitored and repaired via the quota(8) command:

   * quota


Controlling Quota Behavior
==========================

How restrictive quotas will be may be tailored to the needs of
different sites, via the use of several settings in imapd.conf(5):

      "lmtp_over_quota_perm_failure:" 0

         If enabled, lmtpd returns a permanent failure code when a
         user’s mailbox is over quota.  By default, the failure is
         temporary, causing the MTA to queue the message and retry
         later.

      "lmtp_strict_quota:" 0

         If enabled, lmtpd returns a failure code when the incoming
         message will cause the user’s mailbox to exceed its quota.
         By default, the failure won’t occur until the mailbox is
         already over quota.

      "quotawarn:" 90

         The percent of quota utilization over which the server
         generates warnings.

      "quotawarnkb:" 0

         The maximum amount of free space (in kB) at which to give a
         quota warning (if this value is 0, or if the quota is smaller
         than this amount, then warnings are always given).

      "quotawarnmsg:" 0

         The maximum amount of messages at which to give a quota
         warning (if this value is 0, or if the quota is smaller than
         this amount, then warnings are always given).

      "autocreate_quota:" -1

         If set to a value of zero or higher, users have their INBOX
         folders created upon a successful login event or upon
         *lmtpd(8)* message delivery if *autocreate_post* is enabled,
         provided their INBOX did not yet already exist.

         The user’s quota is set to the value if it is greater than
         zero, otherwise the user has unlimited quota.

         Note that quota is specified in kilobytes.

      "autocreate_quota_messages:" -1

         If set to a value of zero or higher, users who have their
         INBOX folders created upon a successful login event (see
         *autocreate_quota*), or upon *lmtpd(8)* message delivery if
         *autocreate_post* is enabled, receive the message quota
         configured in this option.

         The default of -1 disables assigning message quota.

         For consistency with *autocreate_quota*, a value of zero is
         treated as unlimited message quota, rather than a message
         quota of zero.


Quota Database
==============

Quota information is stored either in a database (i.e. twoskip,
skiplist) or in “quotalegacy” format, which is a filesystem hierarchy.
This is controlled by the "quota_db" setting in imapd.conf(5).  Here’s
more about the pertinent settings:

      "quota_db:" quotalegacy

         The cyrusdb backend to use for quotas.

         Allowed values: *flat*, *skiplist*, *sql*, *quotalegacy*,
         *twoskip*, *zeroskip*

      "quota_db_path:" <none>

         The absolute path for the quota database (if you choose a
         single-file quota DB type - or the base path if you choose
         quotalegacy).  If not specified will be
         configdirectory/quotas.db or configdirectory/quota/


Converting Quotas Database
==========================

The cvt_cyrusdb(8) utility may be used to convert between formats.
It’s usage with "quotalegacy" is a special case, in that the first
argument (“<old db>”) will be the path to the *base* of the
"quotalegacy" directory structure, not to a particular file.

For example, given this typical layout:

   /var/lib/imap/
   |            /quota/
   |                  /A/
   |                    /user/
   |                         /bob/

The proper "cvt_cyrusdb" command would be:

   cvt_cyrusdb /var/lib/imap/quota quotalegacy /var/lib/imap/quotas.db twoskip

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