Open a Command Prompt and type the following to test sending mail using SMTP:
(This is used to test that SMTP is working and that port 25 is open.)
telnet mail.domain.ext 25
MAIL FROM: firstname.lastname@example.org (this e-mail address should be the address from the domain that you are testing from)
RCPT TO: email@example.com
Subject:-type subject here- then press enter twice (these are needed to conform to RFC 882)
To tell the mail server that you have completed the message enter a single “.” on a line on it’s own.