Nigel,
> We have a requirement for a mail server (SMTP receive, POP collection,
> IMAP not currently required) with a presence in 2 data centres
Without having thought this out entirely, a database, say Mysql, placed
on shared storage available from both data centres, could feed DBMail
(
http://www.dbmail.org/index.php?page=overview) from which your clients
retrieve their POP messages.
(
http://www.dbmail.org/dokuwiki/doku.php?id=bigpicture)
We've had rather good experience with MySQL on DRBD as shared storage,
but large volumes of updates are a bit slow -- this won't affect you.
No experience as yet with DBMail, although it sounds interesting.
-JP
