[Dovecot] Dovecot strong or not for a big Webmail architecture

[Bill Boebel]

On Thu, August 2, 2007 3:06 pm, John fistack <john.fistack at yahoo.fr> said:

> I know webmail.us use Dovecot, what is the most big dovecot architecture known ?
> Do you think Dovecot can handle 1 million of active users in a good architecture ?

Yep... and we have 500K very active users on it.  We've scaled Dovecot horizontally without NFS, just lots of independent Dovecot server intances with smart proxy/mail-routing infrastructure around it.  It can easily scale to millions of users this way.  Just make sure you throw enough disks at it and you'll be fine, with or without NFS.

> Do you think it's a good solution to use one synchronised local Openldap on each
> server Dovecot ?

No.  I'd replicate your ldap database on a few servers that are dedicated to that purpose, and on each mail server use Dovecot's auth_cach feature to minimize how often it needs to query ldap.
 
> Do you think It's possible to use Postgresql or MySQL instead of Openldap ?

We use MySQL.  MySQL handles frequent writes better than OpenLDAP from our experience.  It is also simpler for us to do replication and troubleshooting because we employ several MysQL gurus already.

> Are cyrus or courrier-imap better solutions ?

Definitely not courier-imap, because of it's lack of indexes.  Not sure about Cyrus.

> Someone say "Zimbra is highly scalable and fast", I think Zimbra could be to heavy
> in this architecture, is Dovecot scalable ?

My opinion is Zimbra is too heavy beccause of the way mail is stored on the backend.  Dovecot with maildir scales out well, and the promise of dbox mail storage format appears that it will make it even more scalable down the road.

Bill