Re: [exim] using MX always

On Tue, 10 Jan 2006 11:37:15 -0800
Jeff Lasman <blists@???> wrote:

> Interesting concept... Are you writing that if we do that we _can_ do
> all routing by MX and don't need to do local routing? I don't see
> how this resolves issues, for example, if our clients use Marc
> Perkel's service.

Ah. I think I may have made an implicit assumption here, that you have
separate machines doing:

- origination of mail (i.e. "outbound")
- handling of inbound mail (i.e. mail hub)

but sharing nameservers.

If you do, then what I was saying about DNS helps, because your
originating machine (e.g. webserver, or some other non-mail-hub
machine) "sees" the DNS as the rest of the world. Only when the DNS
changes to point to the mail hub does it start delivering mail to the
mail hub.

If mail is *originating* on the mail hub (including via smarthosting
etc.) then I guess you do still have the local routing problem. Not
sure of an easy solution in that case. I guess you could run more than
one Exim daemon, with different config files, and only the actual
*delivery* "identity" knows how to route the domains locally. For the
other processes, handling "outbound" mail, they route it by DNS (making
sure authoritative/caching are split as before) which may or may not
route it to the local "delivery" process.

Tim