SMTP server testing at command level

Manually testing an outgoing SMTP server

1) Open a command prompt (Start > Run > CMD > [press enter])
2) At the command prompt type:
TELNET mail.serverdomain.com 25 [press enter] (Please see note below about port 25)
(Replace "mail.serverdomain.com" with the name of the SMTP server)
3) Wait for a "220 Ready" response from the server; if you do not get this response then you may have a firewall blocking port 25 or the mail server may be off line.
4) Type the following set of commands to test the server:
EHLO mail.serverdomain.com [press enter]
(Replace "mail.serverdomain.com" with the name of the SMTP server)
MAIL FROM:postmaster@serverdomain.com [press enter]
(Replace "postmaster@serverdomain.com" with YOUR email address)
RCPT TO:postmaster@serverdomain.com [press enter]
(Replace "postmaster@serverdomain.com" with a valid email address on the server; most servers have a "postmaster@" address)
DATA [press enter]
Subject:Email test - please reply [press enter, then press enter TWICE MORE]
Please reply to this email at postmaster@serverdomain.com [press enter]
(Replace "postmaster@serverdomain.com" with YOUR email address)
. [press enter, you may need to press enter again until you see "250 +OK" message]
QUIT

Note regarding port 25:

Some ISPs will intercept port 25, which can cause some mail servers to subsequently receive incorrect commands. For example, the mail server may respond "500 command unrecognized". In this case we recommend trying an alternative SMTP port - many mail servers will also listen on port 587 instead.)