Connection fails

Question asked by Martin Schaible - 8/31/2022 at 4:06 AM

Answered

Hello,
A customer asked for help. He said, that a mail from somebody does not arrive our mail server.
The mail server of the sending person reported, that the mail can not delivered.
So i checked the smtp log and i found several entries like below. The servers had contact for a short moment and that's it. I don not really understand, what happened.

Any idea?

Thanks!

00:31:34.919 [78.46.10.40][44530125] rsp: 220 mail.netfusion.ch Mon, 29 Aug 2022 22:31:34 +0000 UTC SmarterMail Enterprise
00:31:34.919 [78.46.10.40][44530125] connected at 30.08.2022 00:31:34
00:31:34.923 [78.46.10.40][44530125] Country code: de
00:31:34.923 [78.46.10.40][44530125] cmd: EHLO dedi1840.your-server.de
00:31:34.923 [78.46.10.40][44530125] rsp: 250-mail.netfusion.ch Hello [78.46.10.40]250-SIZE 69905066250-AUTH LOGIN CRAM-MD5250-8BITMIME250-DSN250 OK
00:31:34.923 [78.46.10.40][44530125] cmd: QUIT
00:31:34.923 [78.46.10.40][44530125] rsp: 221 Service closing transmission channel
00:31:34.923 [78.46.10.40][44530125] disconnected at 30.08.2022 00:31:34

3 Replies

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Tony Scholz Replied

8/31/2022 at 9:52 AM

Employee Post Marked As Answer

Hello Martin,

Looking at the log you provided the connecting server is issuing the QUIT command

00:31:34.923 [78.46.10.40][44530125] cmd: EHLO dedi1840.your-server.de
00:31:34.923 [78.46.10.40][44530125] cmd: QUIT

At this point we are doing as requested and closing the session. There is no mail from or any other commands besides EHLO and QUIT.

Thank you

Tony Scholz

Lead Network/System Administrator

SmarterTools Inc.

www.smartertools.com

Martin Schaible Replied

8/31/2022 at 1:05 PM

Hello Tony

The communication of the sending server is suffering somehow, right? The server opens a connection, my server says EHLO and then the sending servers quits. Very strange.

So i asked the person to send a mail to gmail, which worked well.

One issue could be the reason: Some very restrictive admins do not allow to have mail exchange with mail servers using SSL only. They allow TLS only.

Maybe this short communication was a test? I need to talk to the administrator of the sending server.

Yes, we support TLS too, but the customer didn't change yet.

Thak you!

Tony Scholz Replied

8/31/2022 at 2:11 PM

Employee Post

Hello,

It is possible that this is a test or that this is not the one that failed. If you can get a hold of the SMTP Out session from the client this may help. Thank you

Tony Scholz

Lead Network/System Administrator

SmarterTools Inc.

www.smartertools.com

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