Mail Relay Testing

For mail hubs that found themselves a victim of spammers you can check if the relaying is accidentally enabled using MAPS Transport Security Initiative. For testing see Is my mailer vulnerable For fixing information How can I fix the problem. You need to keep your MTA up-to-date. Holes in both sendmail (upgrade to v. 8.12.3 or later is recommended) and IMAP can be used to get root access -- see Relaying of Spam Email through Victim Sites . For sendmail 8.9 some discussion is in Using check_ in sendmail 8.9. For 8.8 in Anti-Spam Provisions in Sendmail 8.8.

Bridge wrote:
> Want to get some detail adive on how to test the that the sendmail daemon running on the is relay disabled? I understand that sendmail 8.9 disabled relay by default, is there a way to test it? Please give some detail. I also would like to have some details on how to prevent sendmail from spam.

Start a shell, then:

$ telnet your_mail_server_name 25
HELO
MAIL FROM: user1@domain1
RCPT TO: user2@domain2

If your mail server has been configured properly, it will say something
about being unable to relay email.

Anonymous

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Last modified: February 28, 2008