Am 05.10.2012 12:42, schrieb Emmanuel Noobadmin:
I've some users that cannot receive emails from a particular domain.
On checking the logs, I see massive ton of incomplete transaction like
this
incomplete transaction (connection lost) from <xxx@xxxx> for yyy@yyy
unexpected disconnection while reading SMTP command from ()
Running a mxtoolbox.com check on the other server seems to point to
the fact the sender's server does not support TLS.
I'm reluctant to disable TLS on exim just because of one sender so
wondering what is the best way to handle such senders?
i know those .. i had those messages for connections from windows to linux.
I don't think TLS will help you or cause it in any way. Disabling will
help you to understand it.
This was the situation i had :
the windows client starts the connection normaly..
SMTP headers got exchanged
SMTP Data got delivered from the windows system
Windows should now send QUIT , but it never happend on our side.
Windows did indeed send it on his side , but it never reached the linux
server, which assumed after the tcp timeout, that the connection got
dropped on the other side.
It was caused by a very odd combination of linux and windows
kernel/tcp/ip stacks,
After a while, that customer involved got a windows update and it
magically worked again, which it didn't do for months.
learned solutions :
update your kernel to something different
update the externel machine to something different.
Details:
it got caused by a specific tcp window size, which both tcp/ip stacks
refused to work with correctly.
The linux kernel devs refused to rework it in the kernel and the
reactions from M$ was to refuse to react to it in any form ( of course ) :)
But, your problem could also be located on the sending server alone. If
you want to find out, you have to work with the admin there and make use
of tcpdump a lot.
best regards,
Marius
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