[CentOS] clustered mail server?

Hi all

I'm looking for a working HOWTO / Tutorial / sample setup of setting up 
a clustered email server. I know I can setup a CentOS cluster with 
Heartbeat & drbd, but I'm not 100% convinced it will work for the email 
as well.

Ideally, I'd like to use an open source groupware server, like say open 
exchange, php groupware, Scalix (free / community version), etc. So, if 
anyone can please point me in the right direction?

I've already setup a heartbeat cluster, and use rsync to sync files for 
Samba, Apache & NFS, and also setup a Master-Master MySQL replication, 
but don't yet know how to setup the email server,

-- 

Kind Regards
Rudi Ahlers
CEO, SoftDux

Web:   http://www.SoftDux.com
Check out my technical blog, http://blog.softdux.com for Linux or other technical stuff, or visit http://www.WebHostingTalk.co.za for Web Hosting stuff