[Dovecot] usernames with/without domain - my solution

[Ian B]

My existing pop3/imap environment is courier imap + vpopmail + qmail with MySQL backend. I'm looking at migrating this to Dovecot.

Currently I have multiple instances of Courier bound to different loopback IPs (the IPs correspond with the virtual IPs on a server load balancer). When a user authenticates they don't have to specify a domain - if they don't, Courier will use a 'default' domain (defined in the Courier config for that instance).

Moving to Dovecot I want to avoid having to running an instance of Dovecot listening on each loopback IP, but still handle usernames that may not have the domain component.

I wasn't able to find any examples showing how to achieve this exactly, so came up with the following solution:

1. create a new 2 column SQL table: 'domain', 'IP' - this allows me to map between the local Dovecot IP and the 'default' domain
2. create a (rather ugly looking) sql query that combines data from both the vpopmail table and the new table

The SQL query is as follows:


SELECT 
  IF('%d' = '',dovecot.domain,'%d') AS authdomain,
  CONCAT(pw_name, '@', pw_domain) AS user, 
  pw_passwd AS password, pw_dir AS userdb_home, 89 AS userdb_uid, 89 AS userdb_gid 
FROM vpopmail, dovecot_authmap AS dovecot 
WHERE  pw_name = '%n' 
  AND  dovecot.local_ip = SUBSTRING_INDEX('%l', ':', -1)  
GROUP BY pw_domain HAVING pw_domain = authdomain


NOTE: I'm prefetching userdb info

This works, however I'd like to know what others think of this approach, and whether there is a better way to achieve what I require.

Thanks,
Ian.


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