OT - Scalable email server solution needed

[Chris Shenton]

robert <bsd at bathnetworks.com> writes:

> Have a look at qmail, It is very scalable and well supported with
> various sites and mailing lists. Iv'e been using it for well over a year
> now.

Most important thing, IMHO, is uptime.  If you use the Maildir mailbox
format you can put it on a solid NFS server like a NetApp and front it
with any number of MTAs and IMAP servers.  Maildir is NFS-safe. 
If a (used) netApp is too expensive for you, the same approach still
keeps your complicated services off your most critical file server.

I used qmail-ldap (qmail with LDAP for virtualization) and a handfull
of 1U SMTP/IMAP/POP/Squirrelmail servers. Each server had a local
read-only replica of the LDAP data sync'd from the LDAP master.  Zero
downtime in well over a year, even with taking individual boxes down
(one at a time) for upgrades and such.

You could also look at Vpopmail virtualization for qmail. I've not
tried to scale that across multiple boxes so I don't know how you'd
replicate the account info.