From iRedMail

Requirements

• Dovecot 1.2.x. If you're using dovecot-1.1.x, please Upgrade Dovecot 1.1.x to 1.2.x first.

Steps

• Replace file based quota by quotadict in /etc/dovecot.conf:

plugin {
    #quota = maildir                          # <- Comment this line.
    quota = dict:user::proxy::quotadict       # <- Add this line.

    # ... SKIP OTHER CONFIG HERE ...
}

• Add quotadict in dict section in /etc/dovecot.conf:

dict {
    quotadict = mysql:/etc/dovecot-used-quota.conf        # <- Add this line.

    # ... SKIP OTHER CONFIG HERE ...
}

• [For OpenLDAP backend] Create MySQL tables used_quota in database iredadmin used to store realtime quota info. (Of course you can use other database instead of iredadmin.)

$ mysql -uroot -p iredadmin
mysql> CREATE TABLE IF NOT EXISTS `used_quota` (
    `username` VARCHAR(255) NOT NULL,
    `bytes` BIGINT(20) NOT NULL DEFAULT 0,
    `messages` BIGINT(20) NOT NULL DEFAULT 0,
    PRIMARY KEY (`username`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

• [For MySQL backend] If you're using iRedMail-0.6.1 or order version, you can simply add two columns in table vmail.mailbox:

$ mysql -uroot -p vmail
mysql> ALTER TABLE mailbox ADD COLUMN `bytes` BIGINT(20) NOT NULL DEFAULT 0;
mysql> ALTER TABLE mailbox ADD COLUMN `messages` BIGINT(20) NOT NULL DEFAULT 0;

Note: Column "bytes" stores size of all mails in user's mailbox, column "messages" stores number of all mails in user's mailbox.

• Create file /etc/dovecot-used-quota.conf. Note:
  • If you're using iRedAdmin with OpenLDAP backend (either Open Source Edition or iRedAdmin-Pro), you can find database user and password in its config file settings.ini, under iRedAdmin installation root directory, in section [iredadmin].
  • Change dbname, table if you're using MySQL backend.

connect = host=localhost dbname=iredadmin user=iredadmin password=passwd
map {
    pattern = priv/quota/storage
    table = used_quota
    username_field = username
    value_field = bytes
}
map {
    pattern = priv/quota/messages
    table = used_quota
    username_field = username
    value_field = messages
}

Note: You can find

• Restart dovecot and it should work as expected now.

Test

• Restart dovecot.
• Restart postfix.
• Log into webmail. Dovecot will update table 'used_quota' when mail arrived or removed.
• Log into phpMyAdmin and check whether there's any records in table 'used_quota'. Sample data:

mysql> select * from realtime_quota;
+----------+-------+----------+
| username | bytes | messages |
+----------+-------+----------+
| www@a.cn |  9907 |        2 | 
+----------+-------+----------+

References

• Dovecot dictionary quota: http://wiki.dovecot.org/Quota/Dict
• Article contributed by @maxie_ro, works with Dovecot-1.1.x