[TriLUG] seeking advice for a bullet-proof mail server

[Ryan Leathers]

My company needs a new mail server.  This server will support various
automation and workflow concerns as well as a light volume of customer mail.
It will be supported by my customer facing organization rather than the
Enterprise IT organization, so I have convinced the decision makers to let
me stray from the IT standard of Microsoft Exchange.  Though I suspect the
volume of mail to be light, it must still be a highly reliable system.  I
would love to be able to make the case for migrating the entire company away
from Exchange someday.

My thought is to use qmail along with qtrap, clam av, and spam assassin.
I'm leaning toward qmail since I know it to be simple to set up and
administer.  That's important since there will be no dedicated mail jockey.
I am also interested in running a second mail server, not for load
distribution, simply for redundancy against failure.  This is where I have
the most questions.  It seems clear to me that setting up two hosts as mail
exchangers and sharing between them via NFS is absolutely not what I need,
yet this is the solution I'm turning up when googling for redundant qmail.
The only way I can imagine this working is if NFS were offering a file
system from a 3rd reliable location to each of the two hosts.  

Does anyone have a good suggestion for me to create some redundancy using
only two hosts?  FYI the hosts themselves are solid hardware with mirrored
disks.  I also have LVS directors in place so that option is definitely on
the table in addition to MX record tricks if I can just determine how to get
the same data on both hosts.  I'm also open to suggestions other than qmail
if there is a good redundancy story specific to some other solution.