Microsoft KB Archive/170471
Article ID: 170471
Article Last Modified on 10/28/2006
- Microsoft Exchange Server 4.0 Standard Edition
- Microsoft Exchange Server 5.0 Standard Edition
- Microsoft Exchange Server 5.5 Standard Edition
This article was previously published under Q170471
The Microsoft Exchange Server Message Transfer Agent (MTA) may return messages back to originators with Non-Delivery Reports (NDRs) that state:
Unable to deliver due to MTA congestion.
These NDRs will be accompanied by the following events logged in the Windows NT Server Event Viewer Application Log:
4284 A error occurred during connection/disconnection. Error code: 8511 [POP4 POP4 DOWN 4 179] (14) 290 A non-delivery report (reason code unable-to-transfer and diagnostic code maximum-time-expired) is being generated for message C=US;A= ;P=Organization; L=Server03-970224213600Z-1460. It was originally destined for DN:/o=organization/ou=sitename/cn=recipients/cn=recipientnameC=US;A= ; P=organization;O=sitename;S=user;G=joe; (recipient number 1); and was to be redirected to . [MTA DISP:RESULT 20 136] (12)
This combination of errors usually indicates a misconfigured MTA and/or connector. To troubleshoot this issue follow these steps:
- Verify that the Windows NT Servername matches the local MTA name.
- Verify that the naming conventions used to communicate between the two servers are functioning correctly.
- If X400 connectors are being used, make sure all the manually entered information is correct on both servers.
If any of these are incorrect, this behavior is by product design.
Keywords: kbinfo KB170471