Replicated Mailboxes

Greetings,

I just wanted some input on creating mailboxes that are replicated across
servers please.

I note that the latest Cyrus mailstore code has support for replicating
mailboxes between servers, so that in the event that one server was to go
offline, or have a disk failure, there is a copy of that mailbox on a
secondary server.

This would be great for implementing high-end email solutions, where it is
critical for the customer to always have access to their email.

One option I considered, is getting Qmail to deliver to Cyrus, by calling
the Cyrus deliver command from .qmail-default, but this solution seems like
a bit of a hack, and obviously wouldn't be as efficient as using the LMTP
solution that Cyrus provides.

The other question I had to put to the news group, was the possibility of
something similar for a vpopmail/courier setup.

One way I was considering, was using an OpenAFS, or Coda filesystem, with
replication, so if one Coda file store was to go offline, the replicated one
could take over. I am not sure how effectively this may work for the
Maildir format though, and if I might run in to any problems doing this. I
know that Maildir is meant to be NFS safe, but not sure if that applies to
Coda also.

Does anyone have any experience in configuring high availability Qmail
installations, and if so, what approach did you take?

Any feedback on this subject will be very much appreciated.

Thanks for your time.