email delivery problem - luv-beginners

20 Apr 2012

I have been asked to investigate a problem with undeliverable emails.

The problem is that email to a particular domain is not being sent but all other emails
from the same server are apparently working correctly. The administrator of the receiving
domain insists that our server is not handing the mail off correctly to the internet.

Our set-up consists of a windows network using a windows 2003 server domain with a gateway
server running Fedora 9 and using Sendmail 8.14.12. Both servers are due for replacement
in the near future.

Mail transport from Outlook on the windows network appears to have no problem using the
mail server, only in the case of this one particular domain does delivery fail. I have
tried sending an email to the "undeliverable" domain and cc'ing it to
another external address. The message failed on one address but succeeded immediately on
the other. The entry in the sendmail log is as follows:

...
  Apr 19 11:51:03 gw sendmail[467]: q3J1p3w2000467:
from=&lt;Administrator(a)yyyyy.com.au&gt;au>, size=1510, class=0, nrcpts=2,
msgid=&lt;64001D94702C3545B284436BFA4D2932457EAB(a)xxx.yyy.local&gt;al>, proto=ESMTP,
daemon=MTA, relay=[192.168.xx.xx]
 Apr 19 11:51:04 gw sendmail[470]: q3J1p3w2000467: to=&lt;xxx(a)zzzz.com&gt;om>,
delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=151510, relay=extmail.zzzz.com.
[xx.x.xxx.xxx], dsn=2.0.0, stat=Sent (Message received:
20120419015104.WMYJ5617.nskntingx06p.mx.zzzz.com(a)gw.yyyy.com.au)
 Apr 19 11:51:07 gw sendmail[470]: q3J1p3w2000467: to=&lt;AAA(a)BBBB.com&gt;om>,
delay=00:00:04, xdelay=00:00:03, mailer=esmtp, pri=151510,
relay=BBBB.com.inbound15.CCCCC.net. [xxx.xx.xxx.xx], dsn=4.0.0, stat=Deferred: Connection
refused by BBBB.com.inbound15.CCCCC.net 
dig finds the correct MX entries for the outside domain and traceroute has no problems
locating the foreign server.

Any suggestions would be gladly received.

Thanks

Michael 