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Are PTR Records Important?

Posted by Cliff on from the legal-spam-fighting-tactic-or-unnecessary-hassle dept.

erfmuffin asks: "I work for a medium-sized regional ISP. Recently we configured our email gateway to refuse connections to IP addresses that do not resolve (ie no reverse DNS). I am amazed at how many legitimate domains use mail servers with no PTR record! At the same time, we have avoided a great deal of junk mail in one swoop. Wouldn't it be better for mankind if all mail servers refused mail from non-resolvable IPs? Should all legitimate mail servers have valid PTR records or has the world become too lazy to make email delivery, easier?"

3 of 138 comments (clear)

  1. Well by Joe+the+Lesser · · Score: 2, Funny

    They are certainly just as important as TPS reports, if not more so.

    Have you sent a memo?

    --
    "I only speak the truth"
    Karma: null(Mostly affected by an unassigned variable)
  2. Re:No it wouldnt be better by Harik · · Score: 4, Funny
    People choose their ISP's for various reasons: price, quality of service, convenience. What kind of drangles they use on their gimlets should not be one of them.
    Quite right! Who cares about standard things like DNS when you can just use WINS! Send packets to the broadcast address and hope the right machine responds.

    Hell, people who want their ISP to support PPP or IPv4 are just being bitchy. Nobody needs more then IPX over SLIP anyway.

    --Dan

  3. Here's an even BETTER idea! by Ashurbanipal · · Score: 4, Funny

    Why not just refuse all messages that come from IP addresses that include the number 68?

    I have analyzed the vast body of spam (for Bayes purposes) that has come through my mailservers over the last year or so, and I find that a lot of spam is sourced from IP addresses that include this number.

    Sometimes it's x.x.68.x, sometimes it's x.n68.x.x, but that evil little 68 just keeps popping up!

    According to my numbers, a greater amount of spam comes from IPs containing 68 or 24 than comes from domains with inconsistent PTRs.

    So, using your own logic, I should just ban all IPs with 68 in them, and tell people with legitimate Email needs that they will have to find a new ISP.

    To paraphrase a previous poster, "The fact that discarding mail from addresses containing the number 68 significantly reduces spam is reason enough that everyone should do so. I too will have to stop using a bunch of numbers I own but, it is worth the effort to stick to this policy. If you have a 68 in your IP, you can't send me mail!"

    Note to moderators: Irony is not the same thing as flamebait...