[plug] email problem

[Adam Hewitt]

Hi All,

This post isn't very linux related but I am hoping that one of you
knowledgeable people would be able to help me anyways.

We have a Lotus Domino server forwarding outbound email to a Trend
Micro IMSS server for processing (spam filtering, appropriate email
scanning etc). The email queue on the Domino server suddenly started
backing up yesterday and *seemed* to be resolved when the server was
stopped, mail boxes deleted and the server rebooted....however this
was at 19:00 last night so the load was not high enough to give
accurate test results.

Today at roughly the same time, the same thing happened. This then
pretty much excluded a corrupted mailbox as previously thought.
However, what I discovered was that if I telnet to the Trend Micro
mail relay on port 25 from the Domino server that although it
connected any command sent was returning a 500: Unknown Command
message. I was able to connect and successfully send an email from a
linux server. I can also connect from the Domino server to the linux
server on port 25 and successfully run smtp commands. Both the Domino
& Trend servers are running Windows 2003.

Then all of a sudden the mail started flowing again on the Domino
server and everything for the last couple of hours is looking ok.

Does anyone have any ideas as to why I would be able to connect from a
linux server to the Trend server on port 25 and send an email, but I
can't run any smtp command from the Domino server? I also tried using
putty on the windows server and although that seems to work, it will
only work after the first error message (ie. I connect, I see the
greeting message, type 'ehlo' and it throws back 500: Unknown Command,
but then running it again works and I can proceed).

This has been doing my head in now for two days and I am ready to
throw the mail server at someone.

Thanks in advance.

Adam.