HA mailserver (smtp, pop3, imap, imap/ssl)

[Saku Ytti <saku-debian-isp@ytti.fi>]

Hello,

We are looking replacement for SunCluster (2*e450) mail server and would
preferally like to do it with x86/linux cluster software can be commercial
or free.

What software are currently used to build these? Requirment is that 
the media is replicated and locking functions properly so we can pop
machines in/out and all user accounts/all mail still works only if
one server is pop out load on other machines just increses slightly.

There can't be any SPOF.

-- 
	++ytti