If you're having problems verifying a mail server from the ColdFusion Administrator, you can telnet to the mail server on port 25 to debug the connection.

C:>telnet smtp.mail.company.com 25

If you find that you are unable to establish a connection from a telnet session when logged on to the server hosting ColdFusion, then ColdFusion will also not be able to do so.

Once you have a connection established on the commandline, you can actually send mail to test problems with the sender's or recipient's address. Be careful when typing as backspace or delete characters are counted.

Here is an example session of sending mail from the commandline: