This documentation is for Dovecot v2.x, see wiki1 for v1.x documentation.


There are different quota backends that Dovecot can use:

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

Enabling quota plugins

There are currently two quota related plugins:

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:

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:

# quotaBytes is exported to $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

This post-login trick unfortunately doesn't work with [:LDA:deliver]. If you need it, you're pretty much out of luck for now. [:Quota/New:v1.1 quota] makes this possible.