No 220 response to telnet on port 25 from certain servers, works fine from others
Hi there,
I'm trying to remotely troubleshoot a problem with an Exchange server (2003) receiving email.
From some machines, telnet to the server works fine, as below:
~ > telnet mail1.server.com 25
Trying 1.2.3.4...
Connected to mail1.server.com.
Escape character is '^]'.
220 mail1.server.local Microsoft ESMTP MAIL Service, Version: 6.0.3790.3959 ready at Fri, 11 Apr 2008 14:47:25 +0100
From other servers, it connects, but doesn't respond with the 220, unless some data is sent (pressing enter, or sending a HELO command) - obviously a server isn't going to do this autommatically.
~ > telnet mail1.server.com 25
Trying 1.2.3.4...
Connected to mail1.server.com.
Escape character is '^]'.
------- just sits here -------
------- if you press enter you get the 220 response -------
220 mail1.server.local Microsoft ESMTP MAIL Service, Version: 6.0.3790.3959 ready at Fri, 11 Apr 2008 14:57:32 +0100
Anyone have any ideas?
I'm trying to remotely troubleshoot a problem with an Exchange server (2003) receiving email.
From some machines, telnet to the server works fine, as below:
~ > telnet mail1.server.com 25
Trying 1.2.3.4...
Connected to mail1.server.com.
Escape character is '^]'.
220 mail1.server.local Microsoft ESMTP MAIL Service, Version: 6.0.3790.3959 ready at Fri, 11 Apr 2008 14:47:25 +0100
From other servers, it connects, but doesn't respond with the 220, unless some data is sent (pressing enter, or sending a HELO command) - obviously a server isn't going to do this autommatically.
~ > telnet mail1.server.com 25
Trying 1.2.3.4...
Connected to mail1.server.com.
Escape character is '^]'.
------- just sits here -------
------- if you press enter you get the 220 response -------
220 mail1.server.local Microsoft ESMTP MAIL Service, Version: 6.0.3790.3959 ready at Fri, 11 Apr 2008 14:57:32 +0100
Anyone have any ideas?
ASKER
It seems to wait forever to send a 220. I have noticed that the longer I wait, the more times I have to press enter to get the banner to appear....
If the cursor just sits there then something is blocking port 25. If you were using some kind of antispam tool then I would expect to see a delay from all locations.
Simon.
Simon.
ASKER
But it connects, so there's nothing blocking 25 !
ASKER
But it connects, so there's nothing blocking 25 !
ASKER CERTIFIED SOLUTION
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How long have you waited before pressing "enter"
Other ideas:
Slow banner response can be caused by any of the following reasons:
" A firewall or packet filtering software is delaying the banner response. In this case, you should perform telnet tests from both sides of all routers to measure the differences in banner response times.
" If SMTP protocol logging is enabled, reverse-DNS lookups are performed on each incoming connection. This functionality affects computer performance.