

Quota
=====


There are different quota backends that Dovecot can use: 

 * >>fs<<: Filesystem quota. 
 * >>dirsize<<: The simplest and slowest quota backend. 
 * >>dict<<: Store quota in a dictionary (e.g. SQL). 
 * >>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 >>userdb<< return the quota setting as an >>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. 


Examples
========




SQL
===



---%<-------------------------------------------------------------------------
# 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'
---%<-------------------------------------------------------------------------



LDAP
====


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 >>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: 

---%<-------------------------------------------------------------------------
#!/bin/sh

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

This post-login trick unfortunately doesn't work with >>deliver<<. If you need it, you're pretty much out of luck for now. >>v1.1 quota<< makes this possible. 
(This file was created from the wiki on 2007-12-11 04:42)
