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Thread: Block IPs that Don't Resolve via Reverse DNS Lookup

  1. #11
    Yves Pires is offline Senior Member
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    Quote Originally Posted by eatickets View Post
    What do you mean by this?
    mail server without reverse DNS configured

  2. #12
    eatickets is offline Active Member
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    Quote Originally Posted by Yves Pires View Post
    mail server without reverse DNS configured
    Half a sentence does not answer my question. Are you trying to say that my email server is poorly configured if it does not have reverse DNS configured? And if that's the case, can you perhaps point me in the direction of setting this up?

  3. #13
    phoenix is offline Zimbra Consultant & Moderator
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    Quote Originally Posted by eatickets View Post
    Half a sentence does not answer my question. Are you trying to say that my email server is poorly configured if it does not have reverse DNS configured? And if that's the case, can you perhaps point me in the direction of setting this up?
    If you have no reverse DNS then you'' need to contact your ISP to create one for you. The fact you've asked the question would (possibly) indicate that you don't have a rDNS or that you didn't set it up. You can check it via a web site or with nslookup: "reverse dns" - Yahoo! Search Results
    Regards


    Bill


    Acompli: A new adventure for Co-Founder KevinH.

  4. #14
    eatickets is offline Active Member
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    Quote Originally Posted by phoenix View Post
    If you have no reverse DNS then you'' need to contact your ISP to create one for you. The fact you've asked the question would (possibly) indicate that you don't have a rDNS or that you didn't set it up. You can check it via a web site or with nslookup: "reverse dns" - Yahoo! Search Results
    I know what reverse DNS is, and I know how to set it up. That's not the question. My question is how much legitimate email will be blocked if I set up rDNS in Zimbra?

  5. #15
    phoenix is offline Zimbra Consultant & Moderator
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    Quote Originally Posted by eatickets View Post
    I know what reverse DNS is, and I know how to set it up.
    Really? The reply I gave was in response to this question:

    Quote Originally Posted by eatickets View Post
    Are you trying to say that my email server is poorly configured if it does not have reverse DNS configured? And if that's the case, can you perhaps point me in the direction of setting this up?
    That seems to be asking how to set-up a reverse DNS unless my understanding of English is different than yours?

    Quote Originally Posted by eatickets View Post
    That's not the question. My question is how much legitimate email will be blocked if I set up rDNS in Zimbra?
    As you run a mailserver you surely know the answer to that question (you can certainly find it via google)? The answer your question will be 'it depends', it will depend on whether the receiving mailserver Admin wants to 'punish' the sending server for being poorly configured. You will, therefore, get some legitimate email rejected by some servers.

    As you already know how to set on up I'd suggest you do that for your current server, if you haven't already. If you have then I'd also suggest you check to see if it's correct.
    Regards


    Bill


    Acompli: A new adventure for Co-Founder KevinH.

  6. #16
    eatickets is offline Active Member
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    Quote Originally Posted by phoenix View Post
    Really? The reply I gave was in response to this question:

    That seems to be asking how to set-up a reverse DNS unless my understanding of English is different than yours?
    That question came from Yves Pires vague instruction:

    mail server without reverse DNS configured
    My impression was they were trying to tell me how to configure something other than what I was already working on. Thus, my question. Your reply, however, merely told me to go use Yahoo. That's not helpful when I'm asking for step-by-step instructions for setting up rDNS in Zimbra.

    Quote Originally Posted by phoenix View Post
    As you run a mailserver you surely know the answer to that question (you can certainly find it via google)? The answer your question will be 'it depends', it will depend on whether the receiving mailserver Admin wants to 'punish' the sending server for being poorly configured. You will, therefore, get some legitimate email rejected by some servers.
    This was all I was looking for. You could have said that upfront and saved all of us the confusion.

  7. #17
    phoenix is offline Zimbra Consultant & Moderator
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    Quote Originally Posted by eatickets View Post
    You could have said that upfront and saved all of us the confusion.
    I was never confused in any of my replies, I was merely answering the questions you specifically asked.
    Regards


    Bill


    Acompli: A new adventure for Co-Founder KevinH.

  8. #18
    eatickets is offline Active Member
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    Quote Originally Posted by phoenix View Post
    I was never confused in any of my replies, I was merely answering the questions you specifically asked.
    Then you must have missed my original post. But thank you anyhow for your help. My manager is trying to get some pros/cons for setting up rDNS to block spam (he's concerned it will block too much legitimate email), hence my post here.

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