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:

220 smtp.mail.company.com ESMTP Sendmail Switch-1.2.3/Switch-1.2.3;
ehlo serat03
250 smtp.mail.company.com Hello [], pleased to meet you
mail from: serat@company.com
250 2.1.0 serat@company.com... Sender ok
rcpt to: stevenerat@nospam.com
250 2.1.5 stevenerat@nospam.com... Recipient ok
354 Enter mail, end with "." on a line by itself
Hey, this is a test of sending mail from the commandline
in a telnet prompt.
250 2.0.0 iAMMipUq021907 Message accepted for delivery
221 2.0.0 smtp.mail.company.com closing connection

Connection to host lost.

To further debug the problem, you could use a network analyzer such as Ethereal to capture or "sniff" the packets between your client and the mail server. Use a capture filter such as "ip host smtp.mail.company.com and ip port 25" to isolate the network trace to only the connection of interest.

Click to view sample network trace