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NDR 5.4.0 Exchange 2K

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5 replies

by jimapp

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I am running Exch 2K on windows 2000. At random I will get an NDR 5.4.0 to an outside address.(DNS error) I can telnet to the domain with no problem from the mail server but for some reason mail can't find its way. Later the mail will go through with no issues. Now it would be easy to blame this on somebody elses mail server but this can happen at any time to any address so the problem has to be at my end. I have tried switching DNS servers to no avail. Any ideas?

5 replies

by volksjager

This may be way off base, but do you have any UNIX boxes that are part of the overall architecture? There is a known bug with Sendmail, that gives this error if a DNS answer is several hundred bytes long. This also explains way the error is intermittent. The version that causes the issue is 8.9.3. To fix upgrade to 8.11.3

by strakovsky

Basically, you provided insufficient info about your network, but I'll try to help anyway.
I suspect you're using your internal DNS server (windows based). I had the similar problem some time ago (before I got rid of Exchange completely;). BTW, Exchange sucks. :)

NDR usually occurs under one of two conditions:
1. The mailserver requests recipient address resolution from DNS server, and receives wrong IP taken from outdated DNS cache.
2. The mailserver requests recipient address resolutionfrom DNS-server, and receives nothing (request or transaction timed out).
Try to read Exchange log to find out what exactly happens. For more info take a look at http://www.ntfaq.com/.
There is no common solution for both of the cases. First leadsyou to DNS server misconfiguration, second shows some networking problem. I think, if you don't want to waste much time playing around, the best suggestion would be to use external well-known DNS server (check up with ROOT or your provider). If error still appears, that certaintly means that you have a connection problem, or your mailserver responce waiting delay is too short.

by jimapp

I appreciate your suggestions. I have even tried other external DNS servers with no luck..strange thing is..if I go to a DOS prompt from the mail server I am able to Telnet to any server that previously gives me 5.4.0 message and if I retry sending to that same mail server I will again get the error message.

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