Exim, relaying and domain expansion.

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Author: Bruce Rodger
Date:  
To: exim-users
Subject: Exim, relaying and domain expansion.


I am using exim 1.61 on one of our campus mail relays.

To deliver mail to departmental systems, we arrange for the the central mail
hub to be the lowest MX,and add explicit routing rules to arrange for the mail
to be forwarded to the departmental system. Therefore no offsite hosts should
contact the departmental systems directly.

However, I have a problem...


for example, consider the domain cad.strath.ac.uk. The lowest MX record
points at the exim host, and there is an explicit entry to reroute this
to its final destination - ie

domainlist:
  driver =domainlist,
  transport=remote_smtp;
    route_file=/usr/exim/configs/domainlist_route_file,
    search_type=lsearch


where domainlist_route_file contains
.
.
cad.strath.ac.uk osiris.cad.strath.ac.uk bydns_a
.
.

ie forward mail addressed to user@??? to the host osiris


mail addressed to user@??? works OK - however mail addressed
simply to user@cad fails. exim -bt gives:

> z@???

z@???
remote delivery to z@???
router = domainlist, transport = remote_smtp
host cad.strath.ac.uk [130.159.232.110]
> z@cad

LOG: 0 MAIN
lowest MX record for cad.strath.ac.uk points to local host
z@cad cannot be resolved at this time:
lowest numbered MX record points to local host
>


ie exim is expanding user@cad to user@???, but not processing
the message in the way I expected it to!

Is there any way (apart from having explicit entries for the "shortened"
hostnames) to get round this?

(yes, I know the best solution is "educate the users - shortened names are
BAD - but thats not the answer I'm looking for....)

Bruce.



-- 
Bruce Rodger                      |Bruce.Rodger@???  PGP key available
Networking and Computer Services  |http://www.strath.ac.uk/CC/People/bruce.html
The University of Strathclyde     | +44 (0)141 548 3460
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