Re: [exim] Distributed Exim servers?

On Tue, Jan 18, 2005 at 11:45:36AM -0000, Piers Kittel wrote:
> I'm trying to set up a number of private networks across the UK, all
> connected to each other by VPN. The current number of networks would be
> 6, and I would like to have 6 Exim servers. I'm aiming to have a single
> email address for all networks - such as one user on Network 1 would have
> joedoe@??? and one user on Network 3 would be janesmith@??? -
> so the Exim server on Network 1 would have joedoe's mailbox and user
> info, and the Exim server on Network 3 would have janesmith's mailbox
> and user info. Is this setup at all possible?

As someone else already wrote, a replicated database of some kind (rsync
or rdist files, use DNS) allows each server to determine if mail should
be delivered locally or to another server. That's no problem.

What you lose is forward cycle detection when using filters, as filters
must run on the machine that holds the storage for a user.

Using a RR set of all six servers for the name of the mail server is
one way for users to submit messages. If you want to be sure that each
user submits the mail to the MTA in its own network, you could have the
DNS server in that network always resolve the name of the mail server
to the local one. Alternatively give the mail server two IPs: One,
that is the same in each network and used to submit messages, and one
that is routed to other networks.

Michael