Weird Telnet Issues

Hello,

We currently have 3 Microsoft Server 2003 boxes. One is a web server,
the other is a mail server, and the third is a file server. The mail
server is having trouble sending to only 1 address so we tried to
telnet to the destination address from the mail server. However, when
we telnet, it connects but IMMEDIATELY disconnects when we type a
character.

This behaivor also happens on the file server. The weird part is we
can telnet just fine to the destination from the web server and
personal computers from inside the network.

We cannot telnet to any servers from the mail and file servers, but can
connect from the web server and other computers within the network.

Anyone have any ideas?

Thanks,
Jason

I forgot to note that this is telnet over port 25 to another mail
server.

Has anyone seen this before? We're still stuck with it

Essentially, there is only 1 e-mail server who can't send to us and
they are using sendmail (we use Exchange).