When I send a message though postfix to clients who have an inhouse exchange server the message never arrives. The strangest thing is it is being delivered as postfix responds with a 250 queued for delivery. Their system administrator can't find the problem so that is not very helpful.

  • Did you guys ever had such an issue and what can be done to counter this?
  • Any common pitfalls that may apply?
  • Or maybe someone has some tips I can give the administrator?

P.s. This issue only happens with inhouse exchange servers.

May 14 00:50:42 mail postfix/smtp[7419]: 25CC31DE9F: to=<[email protected]>, relay=mailcleaner.24dns.nl[]:25, delay=21, delays=0/0/21/0.31, dsn=2.0.0, status=sent (250 OK id=1Uc1YK-00007S-EB)
  • 1
    Well thats confusing. By inhouse you mean both server is under same jurisdiction/owned by same company? Sysadmin on which server? And most importantly where are the logs? And full logs, meaning each line where the message ID appears. Commented May 13, 2013 at 22:19
  • By inhouse I mean the server is located inside their office and is maintained by another IT company. I cannot seem to get any log entries out of them. They say all is fine at their end. I'm just as puzzled as you are. It seems to be just me they can't receive. I posted the question because I was hoping someone else has experienced the same.
    – Bart
    Commented May 13, 2013 at 22:28
  • Logs from postfix, then we can tell if the mail was delivered to exchange or no. Commented May 13, 2013 at 22:41
  • @SandorMarton Added the log entry from postfix. It's delivered to some spam service they use.
    – Bart
    Commented May 13, 2013 at 23:02

1 Answer 1


Yes, the mail left your server.


Are you sure that is the inhouse exchange server? Judging from hostname that looks more like a mail filtering service done by 3rd party? Maybe they started to use now one, changed the mx'es. And now there is a problem between that 3rd part and the exchange.
Or for some reason their exchange marked your mail as Spam and dropped it. But that should be in the exchange logs.

  • Thanks for your answer. I will check with the client and IT company to get some info from them. B.T.W. Are there filtering services that silently drop spam? Seems a bit strange to do so.
    – Bart
    Commented May 13, 2013 at 23:21
  • Could be some different problem between the 2rd party and exchange. But some filtering services may drop silently. Or place in quarantine and sending (to the user) a link to release the mail if he wants. Commented May 13, 2013 at 23:46
  • I contacted them and suddenly it's solved. Still not sure what went wrong but I guess that's their issue, not mine.
    – Bart
    Commented May 14, 2013 at 8:43

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