HELP! Exchange 2003 problem - urgent

[TheFopp]

Hi all got an issue with Exchange 2003 running on a Server 2003 box.

Has been running fine. No changes to the system, but suddenly people started getting NDR reports from the postmaster service on the Exchange box.

Looked in System manager and there are plenty of messages either queued or retrying but none seem to be going out.

Have tried rebooting exchange twice. Have restarted all the Exchange services and the SMTP service to no avail.

Emails are coming in to the system and being delivered to our users without issue and emails sent internally are fine, just sending to external addresses is borked.

Had a few of the following type of errors in the Application Event Log:

A non-delivery report with a status code of 5.4.0 was generated for recipient rfc822;ericforder@bauer.hieber.com (Message-ID <746D4CA7ABE6B2419C4BA59B00EEAC0B01E648A6@exchange .CSM.Local>).
Causes: This message indicates a DNS problem or an IP address configuration problem
Solution: Check the DNS using nslookup or dnsq. Verify the IP address is in IPv4 literal format.
For more information, click http://www.microsoft.com/contentredirect.asp.

and these appeared around the time that it stopped working we thing, but not had any of these errors since reboots, yet the problem still persists.

Guessing it might be DNS based problem, but no changes have been made and there doesn't appear to be any other DNS issues across the network.

Any help would be much appreciated as we are stumped!

[Dos_Box]

Can you sucessfully resolve external IP adresses and domains from the Exchange server using ping, nslookup etc?

[TheFopp]

Can you sucessfully resolve external IP adresses and domains from the Exchange server using ping, nslookup etc?

Hi Dos_Box

Yes, we can resolve external IP and domains using ping and nslookup.

[TheFopp]

bump.... really need some help if anyone has suggestions.

[TheFopp]

Sorted......


...... Cisco routers NBAR policy had gone doolally and was randomly try to block SMTP stuff on Port 25.
Rebooted it and emails are now going out once again.