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Mail Gets Stuck In Delivery Queue 451 4.4.2 [internal] connection closed by remote host

Created: 15 Jan 2013 • Updated: 23 Jan 2013 | 3 comments
Jordanco's picture
This issue has been solved. See solution.


I have the this problem mostly (99%) with mails sent to Yahoo (451 4.4.2 [internal] connection closed by remote host).I have searched the error code but i could only find problems related to cisco firewalls at the gateway and outbound STMP filtering on the firewall which in our situation is not the case.The SMG is an appliance 8340 with 10.0.1-2 version installed.

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Art_P's picture

The reason you are not finding much information is because the issue is outside of the messaging gateway. The error is telling you that the Messaging Gateway was able to connect to the next hop and start a conversation, but the network connection was truncated by a source other than the Messaging Gateway. As per your research, this is often due to Firewalls or Intrusion Detection Systems affecting the network; however, it can also be due to malfunctioning network equipment.

You will want to research this at the network level. The best option is to log your network traffic between you and the end recipient and review those logs to determine the source of the issue.


Jordanco's picture

Thanks for the reply.Will "smtp conversation logging" help ?or any other logging/troubleshooting on the BMG side ???

Jordanco's picture

Increasing the connection time (delivery setings) solved the problem