I have a web server with pages that email forms. I used SMTP to connect to our Exchange server. This recently stopped working. On further investigation I found that the web server cannot telnet the exchange server on port 25, I then started the local SMTP server and I could not telnet the localhost on port 25. I can ping sucessfully.
From my own desktop I can telnet the email server on port 25. I have disabled all antivirus software and firewalls.
The exchange server is running on Windows Server 2003. The webserver is Windows 2000 Server SP4 running IIS.