Open a telnet session: From a command prompt, type telnet, and then press ENTER.
Type set local_echo on a computer running Microsoft Windows® 2000 Server or SET LOCALECHO on a computer running Windows Server™ 2003 or Windows XP, and then press ENTER. This command allows you to view the responses to the commands.
Type o <your mail server domain> 25,and then press ENTER.
Type EHLO <your mail server domain>, and then press ENTER.
Type MAIL FROM:<sender@domain.com>, and then press ENTER. If the sender is not permitted to send mail, the SMTP server returns an error.
Type RCPT TO:<recipient@remotedomain.com>,and then press ENTER.If the recipient is not a valid recipient or the server does not accept mail for this domain, the SMTP server returns an error.
Type DATA.
Type SUBJECT: <subject>.
If desired, type message text, press ENTER, type a period (.), and then press ENTER again.
If mail is working properly, you should see a response similar to the following indicating that mail is queued for delivery: