Sometimes you want to check to see if you have access to an email server directly. A check like this may be necessary on some DSL networks where the ISP will block port 25, which is the standard port that email servers listen in on, due to issues with SPAM and rogue servers.
You can do the check from the command line with a program called telnet:
telnet mail.example.com 25
For mail servers with a Barracuda mail server, you may get a response like:
220 mail.example.com ESMTP (19a38e746d4fc812318d47ee6fa159ea)
Here is a sample session:
mail from:sender@example.com
250 2.1.0 sender@example.com... Sender ok
rcpt to:recipient@example.com
250 2.1.5 recipient@example.com... Recipient ok
data
354 Enter mail, end with "." on a line by itself
subject: Test Message
to: recipient@example.com
This is the body of the message.
.
250 2.0.0 kAEK9vHC005225 Message accepted for delivery
quit
221 2.0.0 mail.example.com closing connection
