I came across an odd feature with MX lookup and exim 2.05 and I'm just
curious to know if this an exim bug.
When using lookuphost, exim failed to deliver to the highest preference
MX entry. The DNS looked like this:-
The mx records for this domain looked like this:-
cmht.nwest.nhs.uk MX preference = 10, mail exchanger =
gatekeeper.cmht.nwest.nhs.uk
cmht.nwest.nhs.uk MX preference = 20, mail exchanger =
mailrouter1.man.ac.uk
cmht.nwest.nhs.uk MX preference = 30, mail exchanger =
mailrouter2.man.ac.uk
cmht.nwest.nhs.uk MX preference = 40, mail exchanger =
mailrouter3.man.ac.uk
cmht.nwest.nhs.uk MX preference = 50, mail exchanger =
mailrouter4.man.ac.uk
cmht.nwest.nhs.uk MX preference = 50, mail exchanger =
gatekeeper.cmht.nwest.nhs.uk
gatekeeper.cmht.nwest.nhs.uk internet address = 193.60.159.61
mailrouter1.man.ac.uk internet address = 130.88.13.7
mailrouter2.man.ac.uk internet address = 130.88.210.1
mailrouter3.man.ac.uk internet address = 130.88.200.93
mailrouter4.man.ac.uk internet address = 130.88.200.94
The problem was that exim ignored the MX record at preference 10 and
instead delivered to "mailrouter1.man.ac.uk" which has preference 20
(the next highest). gatekeeper.cmht.nwest.nhs.uk was accepting mail
during this time.
This happened because there were two MX records for
gatekeeper.cmht.nwest.nhs.uk, one at preference 10 *and* one at 50.
Obviously the DNS config doesn't make sense so the fix was to remove the
MX duplicate record of preference 50 for gatekeeper.cmht.nwest.nhs.uk.
So why did exim ignore the duplicate MX record?
--
Richard Gould
MultiThread Consultants Ltd
http://www.multithread.co.uk
Tel: +44 (0) 1449 678 000 Fax: +44(0) 1449 774 674
email: richard@???
