This documentation is for Dovecot v2.x, see wiki1 for v1.x documentation.
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user_attrs = homeDirectory=home,uidNumber=uid,gidNumber=gid,quotaStorage=quota user_attrs = homeDirectory=home,uidNumber=uid,gidNumber=gid,quotaDovecot=quota


There are different quota backends that Dovecot can use:

  • [wiki:Quota/FS fs]: Filesystem quota.
  • [wiki:Quota/Dirsize dirsize]: The simplest and slowest quota backend.
  • [wiki:Quota/Dict dict]: Store quota in a dictionary (e.g. SQL).
  • [wiki:Quota/Maildir maildir]: Maildir++ quota. This is the most commonly used quota for virtual users.

See ["Quota/New"] for Dovecot v1.1 / quota-rewrite patch quota configuration.

Enabling quota plugins

There are currently two quota related plugins:

  • quota: Implements the actual quota handling and includes also all the quota backends.
  • imap_quota: For reporting quota information via IMAP.

Usually you'd enable these by adding them to the mail_plugins settings in the config file:

protocol imap {
  mail_plugins = quota imap_quota
protocol pop3 {
  mail_plugins = quota
# In case you're using deliver:
protocol lda {
  mail_plugins = quota

Configuring quota

Most of the quota backends have very similar configuration. They support two kinds of quota limits:

  • storage: Quota limit in kilobytes.

  • messages: Quota limit in number of messages. This isn't probably very useful.

You can configure quota globally by placing the settings in plugin section in dovecot.conf and you can give per-user limits by having your [:UserDatabase:userdb] return the quota setting as an [:UserDatabase/ExtraFields:extra field]. The userdb quota setting always overrides the global plugin setting.

The important thing to remember is to use the correct format for quota setting. You can't just return a numeric quota field from userdb and expect it to work. Dovecot wouldn't then know what quota backend to use.

Here is an example global quota configuration:

plugin {
  # 10 MB + 1000 messages quota limit
  quota = maildir:storage=10240:messages=1000

Now if you want to override this for some users, make your userdb return quota field in the exact same format. See below for some examples.



# MySQL, quota in kilobytes:
user_query = SELECT home, uid, gid, concat('maildir:storage=', quota_kb) AS quota FROM users WHERE userid = '%u'

# MySQL, quota in bytes:
user_query = SELECT home, uid, gid, concat('maildir:storage=', floor(quota/1024)) AS quota FROM users WHERE userid = '%u'

# PostgreSQL, SQLite, quota in kilobytes:
user_query = SELECT home, uid, gid, 'maildir:storage=' || quota_kb AS quota FROM users WHERE userid = '%u'


The easiest way from Dovecot's point of view is if you already have the quota in Dovecot's format in LDAP (e.g. maildir:storage=102400. Then you can use a configuration like this:

user_attrs = homeDirectory=home,uidNumber=uid,gidNumber=gid,quotaDovecot=quota

Unfortunately usually this isn't the case. So if you have the quota in kilobytes in LDAP, you can use it in a bit kludgy way:

user_attrs = homeDirectory=home,uidNumber=uid,gidNumber=gid,quotaKb=quota=maildir:storage

If you have the quota stored as bytes, you'll need to use a [:PostLoginScripting:post-login scripting] trick to use them. Something like:

# quotaStorage contains the quota in bytes. It's exported into
# $QUOTA_BYTES environment.
user_attrs = homeDirectory=home,uidNumber=uid,gidNumber=gid,quotaBytes=quota_bytes

And make imap's mail_executable point to a script:

export QUOTA=maildir:storage=`expr $QUOTA_BYTES / 1024`
exec /usr/local/libexec/dovecot/imap

None: Quota (last edited 2021-06-15 23:54:28 by MichaelSlusarz)