??: [Exim] Exim as transparent "proxy"?

> Is it possible to set up exim in conjunction with ip diverting or
> policy routing to intercept SMTP connections/sessions that
> attempt to leave a network? Something similar to ye olde
> transparent proxy for HTTP?

I see no troubles to do it. Just direct all SMTP traffic to server you want.
Needness of special HTTP transparent proxy explains by need to save
destination IP address of connection. For SMTP destination IP is not
important.

> Reason I ask is that I need to find a way to allow all our internal
> mailservers to deliver to each other directly using DNS lookups
> rather than forcing them to use a relay yet still have the relay
> systems (exim) handle deliveries to the larger Internet. Visiting
> each mailserver and hardcoding lists of domains for which to use
> the relay (or not) isn't an option owing to the sheer number of
> mailservers involved. NAT has already been considered and
> rejected.

Really it is a bad idea. You have to now all your mailservers if you are a
system administrator of your company. If you aren't, I guess your company is
bad organized and everyone acts as he wants.