Re: [Exim] looking up different MX records for a domain

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Author: Paul Makepeace
Date:  
To: exim-users
Subject: Re: [Exim] looking up different MX records for a domain
On Mon, Oct 07, 2002 at 09:46:08AM +0100, Philip Hazel wrote:
> On Mon, 7 Oct 2002, Paul Makepeace wrote:
>
> > I can't figure out how to pass on routing info to exim that it treats
> > like MX though, with multiple machines and different priorities. Is this
> > possible? If not, with some C hacking?
>
> Only at one level. Set up your mail hub to the primary host(s), and use
> fallback_hosts to specify the secondary host(s).


At the risk of labouring the point a bit: so are the colon-separated
hosts listed in route_data tried in the same way as MXs of (numerically)
increasing priorities? What is the interaction between multiple hosts in
the route_data and fallback_hosts?

**
On fallback_hosts:

If there are a collection of domains and domain-specific hosts, A H1:H2;
B H3:h4:H5; C H6 etc it doesn't strike me fallback_hosts are much use in
this general situation since it's an unexpanded string, and not
selectable based on input data. It seems to me from my probably limited
understanding that fallback_hosts is really intended for use in a sort
of "hot potato" situation to get the messages off to a limited
collection of peer machines. Is this a fair assessment or am I missing
something?

> One thing that is missing from Exim 4 is the ability to say "route
> domain X as if it were domain Y". This is on the Wish List. If it were
> implemented, you could just set up MX records for "domain Y".


This would completely solve it, AFAICS.

OK, so for today, to share route_list info across multiple hubs does my
TXT hack seem reasonable? (I didn't like it at first aesthetically but
options seem limited.)

A IN TXT H1:H2
B IN TXT H3:H4:H5
C IN TXT H6
etc? I'm assuming this is order of magnitudes quicker than a remote
MySQL lookup.

Thanks for the explanations!

Paul

--
Paul Makepeace ....................................... http://paulm.com/

"If I stuff it in, can you remind me to let go, then it will always
stick to us."
-- http://paulm.com/toys/surrealism/