You received a Non-Delivery Report (NDR) from Symantec Hosted Mail Security (SHMS). You seek steps to troubleshoot and resolve this mail delivery issue.
Symantec Hosted Mail Security was not able to deliver the message to its intended target recipient at the intented target mail domain.
Please examine the text of the Non-Delivery Report to determine the cause of the issue. Several common NDR's from SHMS are listed below...
- 421 p03c11o141.symantecmail.net Service closing transmission channel
Interpretation: This message merely indicates that SHMS issued a QUIT command after some other failure occurred during the SMTP conversation. If possible, look for another, more exact message in the NDR.
- 451 Connection error,
Interpretation: This message indicates that some connection problem occurred during the SMTP conversation. If possible, look for another, more exact error in the NDR.
- 451 Timeout trying verify RCPT
Interpretation: SHMS sent a RCPT TO: command, and the recipient mail server disconnected or timed out at this point during the SMTP conversation.
Resolution: Please contact the administrator of the target domain and work with them to arrive at a resolution.
- connect to <
>.inbound10.symantecmail.com< >: Connection refused
Interpretation: This NDR actually originated at a server attempting to communicate with SHMS. SHMS refused to accept the connection, or a network routing issue occurred somewhere between the server attempting to send the message and the servers of the SHMS mail server array.
Resolution: Please check network connectivity between the sending mail server and the mail servers in the SHMS array using the traceroute or tracert commands. If no network connectivity or routing issue is found, please contact Symantec Technical Support for further assistance.
- 451 unknown error 421 timeout reading from dot response from backend message
1. SHMS connected to the mail server of the target email domain.
2. SHMS sent a MAIL FROM: command, which was accepted by the target mail server.
3. SHMS sent a RCPT TO: command, which was accepted by the target mail server.
4. SHMS sent a DATA command, which was accepted by the target mail server.
5. However, the connection timed out after the target mail server sent a 354 SMTP response to the DATA command, but before SHMS reached the end of the message and sent
. to end the DATA command.
Resolution: Contact the administrator of the target mail domain for additional assistance.
If you have a NDR message not listed here, please search the Symantec KB. If you are unable to locate any relevant documenation or you need to determine the IP address of the mail server where SHMS connected, please contact Technical Support for further assistance.