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have you any AV installed ?
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Check your queues. You may be bombarded with processing spam and/or System Administrator messages. &nbsp;How is the system resources being handled? &nbsp;Any high CPU or RAM?<br />
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I have seen Symantec Antivirus Corporate Edition (the server antiv, not the Exchnage aware version) setup incorectly by having the SMTP option enabled, which blocked port. &nbsp;You stated you didn't have antiv as the issue, but just making sure you weren't just talking about Exchange aware antiv only.
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Check your queues. You may be bombarded with processing spam and/or System Administrator messages.  How is the system resources being handled?  Any high CPU or RAM?

I have seen Symantec Antivirus Corporate Edition (the server antiv, not the Exchnage aware version) setup incorectly by having the SMTP option enabled, which blocked port.  You stated you didn't have antiv as the issue, but just making sure you weren't just talking about Exchange aware antiv only.

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Did you change the SMTP port. Check the properties of the default smtp Virtual Server.<br />
Are you running any other SMTP serices? Are you running Surfcontrol Surfmail Spam filtering softare on your Exchange Server? Or are you running anyother Anti-spam filtering software like Antigen, IhateSpam, GFI Essentials.<br />
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NITADMIN
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Did you change the SMTP port. Check the properties of the default smtp Virtual Server.
Are you running any other SMTP serices? Are you running Surfcontrol Surfmail Spam filtering softare on your Exchange Server? Or are you running anyother Anti-spam filtering software like Antigen, IhateSpam, GFI Essentials.

NITADMIN

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Our Exchange 2003 server suddenly stopped receiving incomming mails. I cannot telnet to port 25, just get a flashing cursor, as soon as &nbsp;I type anything it disconnects the telnet session. No Mcafee or Symantec virus checkers installed. Restarted server, issue still remains. No ports blocked, telnet internally and externally causes the same issue.<br />
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Our Exchange 2003 server suddenly stopped receiving incomming mails. I cannot telnet to port 25, just get a flashing cursor, as soon as  I type anything it disconnects the telnet session. No Mcafee or Symantec virus checkers installed. Restarted server, issue still remains. No ports blocked, telnet internally and externally causes the same issue.



Unable to Telnet to Exchange server on port 25

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.