Problem receiving email

[egthkaatam]

Hi,

I am using the Ironport C-150. One of the sender sometimes cannot send me the email. The log about the failed email is "Incoming connection lost". The sized for the email is just about 100K. Even the email successfully arrive, the last event in the log is also "incoming conneciton lost". Please help. Thanks.

[Andreas Mueller]

Hello Steven,

when you state that the email arrives succesfully, do you mean it has been deliveredto the recipients mail box? In other words, does the "connection lost"  error occur at the beginning of the connection, or at the end?

Regards,

Andreas

[egthkaatam]

Hi Andreas,

This msg occurs at the end of connection. According to the injection debug log, the connection disconnect after the "DATA" command.

[Andreas Mueller]

Hello Steven,

that's most likely a problem with the MTU path discovery not working because the sender or you have blocked ICMP on the firewall. You can test by temporarily decreasing the MTU size on your interfaces (CLI: etherconfig->MTU) as described in knowledge base article 1764 http://tinyurl.com/3w3exdz Default size is 1500, so try with 1400 instead. If that works you have found that the problem is related to MTU, in this case you'd need to find where ICMP is blocked.

Hope that helps,

Andreas

[angfe.landagan]

hi steven,

   you can do some testing with no attachments/ with attachments and see the results;

   you can try also sending same email content to another recipient and see if how the message logs behave.

   incoming connection is lost could be have lots of instances as to why it happened;

my two cents;

agl

[egthkaatam]

Hi Angfe,

It seems that it is not related to the attachement. The mail fail even no attachement. Only email from a domain have such error. Thanks.