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Cannot telnet to Port 25 on Exchange

By mlacombe ·
I'm having some problems telnetting from other servers on the same subnet to port 25 on the mail server(s).

Some servers will work, other's won't. All the client PC's work perfectly fine.

We think we've narrowed down the problem to the exchange server(s) themselves, but cannot locate anything that would be causing this on the server.

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by cmdrkruge In reply to Cannot telnet to Port 25 ...

Which version of exchange and which windows OS is running.

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by cmdrkruge In reply to

When you say that some servers will work and some will not do you mean that for example:

Server A can telnet to port 25 on server B
Server C can telnet to port 25 on server B
Server D cannot telnet to port 25 on server B
Server A can telnet to port 25 on server D
Server C can telnet to port 25 on server D
Server B cannot telnet to port 25 on server D

Server B and D are exchange servers?

Can you clarify?
Are there any events in the event logs at the times when you attempt to telnet.

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by mlacombe In reply to Cannot telnet to Port 25 ...

Windows 2003 Server and Exchange 2003 Enterprise.

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by CG IT In reply to Cannot telnet to Port 25 ...

here's the MS KB article on SMTP telnet test for Exchange 2003.

if you can't telnet in to test exchange there there is something wrong with the SMTP service or port 25 is somehow blocking the traffic.

if you can log on to the exchange server locally, try the telent from there. least that will narrow down where the problem might be. A good telent from the local exchange machine means it can communicate with itself so the problem is inbound to exchange rather than exchange itself.

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by CG IT In reply to
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by mlacombe In reply to Cannot telnet to Port 25 ...

The problem isn't with port 25. Unless there's restrictions set that I don't know how to configure. I can telnet from all my user systems and a few of the other servers perfectly fine. However there are other servers, that are part of the same subnet that I can't connect to the mail servers from.

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by yinbig In reply to Cannot telnet to Port 25 ...

Some AV vendors put in port blocking by default in the distribution (like McAfee). Check your AV settings for such hidden info. Also check the open realy allowed lists on the servers SMTP(port 25 telnets). What about the 2003 firewall?

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