What does it mean when I telnet to a mail server and nothing is displayed?

LB1234
LB1234 used Ask the Experts™
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We have two exchange 2007 servers, one old and one new.  The old one has no mailboxes on it, the new one has all user mailboxes.  I'm trying to use a third party program that takes phone messages and file attaches them to email, sent via our internal exchange server.  When I telnet to the old exchange server, i get several responses, however, when sending to the new server i get a blank screen, and any character entries immediately put me back at a C:\ prompt.  What would be causing this?  What can i do to troubleshoot this problem?  Obviously once the new mail server responds to telnet, the 3rd party app will be able to work. Thanks!
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Commented:
Make sure that port 25 is congigured on the recieve connectors. In The RMC , recieve connector proerties you can check  the same
have configured recieve connector?

Commented:
I suppose you telnet to port 25 to check if the service is answering, not the real telnet port ?
cmd> telnet exchange_server 25


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Sounds like authentication issue.  Try creating a connector that only allows the ip address of the 3rd party server trying to relay and choose externally authenticated.  After that change, restart the Microsoft Exchange Transport Service and then give it a try.
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Commented:
If you get a blank screen - nothing at all, then that means either you are telnetting to the correct IP address or something is blocking it. Even if the authentication was stuffed up you would still get the banner - as a connection needs to be made before authentication can be attempted.

McAfee AV for example will block port 25 in such a way that a telnet test will fail.

Simon.

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Commented:
Is there any setting on that server itself that would disallow a successful telnet test on port 25?

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Commented:
Would I do a packet trace at this point?
can you post a netstat -an from the server?
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Commented:
If the SMTP Server service wasn't running, then you wouldn't get a blank flashing screen. It would return immediately with connection failed. You can do that for yourself by telnet to port 25 of a system you know doesn't have SMTP - like a workstation.

A blank screen means the connection is trying to be made but is being blocked.

Simon.

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