Using Telnet to test SMTP

We normally use telnet to open up a connection to the smtp server to send/retrieve the mails. Below is an example of the commands used..

telnet mail.domain 25
Trying ???.???.???.???...
Connected to mail.domain.
Escape character is '^]'.
220 mail.domain ESMTP Sendmail ?version-number?; ?date+time+gmtoffset?

be polite and give the smtp server a 'hello' although the mail server would take your word for it as of RFC822-RFC1123

HELO local.domain.name
250 mail.domain Hello local.domain.name [loc.al.i.p], pleased to meet you

lets send an email..

MAIL FROM: mail@domain.com
250 2.1.0 mail@domain.com... Sender ok
RCPT TO: mail@otherdomain.com
250 2.1.0 mail@otherdomain.com... Recipient ok

If it doesn't please see possible problems.

To start composing the message issue the command DATA

If you want a subject for your email type Subject:-type subject here- then press enter twice (these are needed to conform to RFC 882)

You may now proceed to type the body of your message

To tell the mail server that you have completed the message enter a single "." on a line on it's own.

.
250 2.0.0 ???????? Message accepted for delivery

You can close the connection by issuing the QUIT command.

quit
221 2.0.0 mail.domain.ext closing connection
Connection closed by foreign host.

Here are a list of problems that i have encountered before....

The domain that you are sending from must exist

501 nouser@nosuchplace.here... Sender domain must exist

A recipient has been specified before a sender.

503 Need MAIL before RCPT

The mail server has refused to relay mail for you, this may be for any number of reasons but typical resons include:
Not using this provider for an internet connection and/or
Not using an email address provided by the owner of the server.
ACL in the mail configuration.

550 mail@domain.ext... Relaying Denied