Ok here is the problem.

I work for a small WISP and we are updating our equipment after breaking away from our parent company. We have just puchased some new dell servers and have made one of them our mail server, but what we want to do is set up another server so that it will load balance and act as a redundant mail server should the main server go down. We are running RHE3 with qmail and squirrelmail. Does anyone know how to do this or if it is even possible to do. Thanks for the time.

What about purchasing RH Cluster Suite? I believe you could do this using ipvs that comes with the RHCS toolset. Try looking through the documentation page on redhat's site http://www.redhat.com/docs/manuals/csgfs/

I just went to a RH class on this stuff and we set up failover apache servers. Should work the same really for mail I think.

However, if you're strapped for cash, I'm sure there are other options for this. One dirt cheap thing would be just manage it though heartbeat scripts to update DNS and bounce a hostname back and forth. Not very elegant but it could work. I just use a round-robin DNS entry to point to both IPs.