Redundant email servers

["Eli B" <elib@shocking.com>]

I have two servers, both i386 boxes running debian in different data
centers that are completely independent of each other. I use the first
server for email (SMTP/IMAP/POP3) and would like to make the second one a
redundant server for the first. In a perfect world as soon as the first
server went down, dns would change quickly enough that most servers would
be redirected to the second server, where their email would be mirrored. I
understand that it\'s not an easy task, but I wondered what I could make
work. It\'s easy enough to rsync everything over ssh, but my real problems
are how can I make the hostnames fail over, which machine has the latest
data etc. Every time I begin to plan how I would like to do it, I run into
problems that I\'m not sure how to solve.

Has anyone done this? Is it possible? Is there a package or two that I can
apt-get which will do it for me? ;) Didn\'t think so.

I\'m dealing with a VERY low volume of email here, around 20 active users.
They are all friends and family though, so any time there is the slightest
network hiccup or god forbid something really breaks, I hear about it from
every one of them.

Thanks in advance,
    - EliB