Description: SMTP command-line test tool swaks (Swiss Army Knife SMTP) is a command-line tool written in Perl for testing SMTP setups; it supports STARTTLS and SMTP AUTH (PLAIN, LOGIN, CRAM-MD5, SPA, and DIGEST-MD5). swaks allows to stop the SMTP dialog at any stage, e.g to check RCPT TO: without actually sending a mail. . If you are spending too much time iterating "telnet foo.example 25" swaks is for you.
A very important tool which makes debugging e-mail a breeze. A must for every mail admin.