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Proving You Are Not a Spammer?

Posted by Cliff on from the smtp-from-header-validation dept.

tfinniga asks: "A spammer has recently started using my domain name as 'From:' addresses when sending out spam. I'm worried about my domain being blacklisted, and I'm annoyed by the bounces — I'm getting about 1000 bounce messages a day. Unfortunately, I give out a different email address to each site I visit: slashdot@example.com, paypal@example.com, amazon@example.com, etc., and the spammer is using a different address for each mail, so simple address filtering doesn't work. What is the best way of avoiding being put on a blacklist, and dealing with the flood of bounces?"

6 of 127 comments (clear)

  1. SPF, backscatter howto by Michael+Wardle · · Score: 5, Insightful

    If the sender is forging your From address, chances are they're not using your mail server. Most decent blacklists (e.g. SpamCop, Spamhaus) will blacklist the offending server's IP address, not your mail domain.

    Consider implementing SPF (home page wiki) so recipient mail servers can drop the message if it wasn't sent from a server authorized to send mail from your domain.

    Most bounce messages will not include your outgoing server's signature. You can consider dropping those messages using the techniques described in the Postfix Backscatter Howto.

  2. Re:This is oddly close to home.... by Anonymous Coward · · Score: 2, Insightful

    There are 6 billion people on this planet. It would be very strange, if multiple similar events did not happen at any given time.

  3. Re:me too by Anonymous Coward · · Score: 3, Insightful

    No, but if I saw a guy going around kicking random people because someone once kicked him, you can be sure that I'd give him a good talking to, and if he didn't stop then... Well ok, so the analogy kinda breaks down here, since I wouldn't actually kick him back. But if there were some devilishly cunning way to trick him into kicking himself, you can be damned sure I'd do that.

  4. Re:me too by DrHyde · · Score: 3, Insightful

    Actually he *has* done something to a spammer. If I were to get 100 auto-replies when I send someone a message, those would be Unsolicted Bulk Email - that is, spam. The guy with his funky auto-responder *is a spammer*.

  5. Re:me too by geminidomino · · Score: 3, Insightful

    Wrong.

    The recipient of the backscatter abuse received unsolicited (he never sent mail to the asshat's domain) bulk (100 messages for 1 sent) email.

    He didn't do anything to the ORIGINAL spammer. He taught a moron script-kidde-turned-spammer a valuable lesson.

  6. Re:me too by Gr8Apes · · Score: 2, Insightful

    The only things that have come back to me are idiot users that don't know what a forged header is. That would be about 99% of the current internet users....
    --
    The cesspool just got a check and balance.