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    Gmail and smtp over IPv6 FYI

    Scheduled Pinned Locked Moved IPv6
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    • C
      Criggie
      last edited by

      FYI - google won't accept email via smtp over IPv6 if you don't have a reverse DNS v6 record for your mailserver's v6 address.

      Having a valid SPF record with IPv6 included isn't sufficient.

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      • johnpozJ
        johnpoz LAYER 8 Global Moderator
        last edited by

        Do they accept email from ipv4 if you don't have a reverse?  I don't believe many major players well accept mail from your mail server if you don't have a ptr, and quite often it better match your forward (FCrDNS)

        ie if your mail server reports its name as smtp.domainX.tld then your PTR better report smtp.domainX.tld as well when they check the IP you connected to them from.

        So are you saying gmail accepts mail from your mail server if you don't have a ptr on your IPv4?

        An intelligent man is sometimes forced to be drunk to spend time with his fools
        If you get confused: Listen to the Music Play
        Please don't Chat/PM me for help, unless mod related
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        • C
          Criggie
          last edited by

          @johnpoz:

          So are you saying gmail accepts mail from your mail server if you don't have a ptr on your IPv4?

          Good point - I suspect a lack of some kind of reverse lookup would contribute to the "badness" of the connection.

          My point is that my ISP doesn't have a reverse nameserver assigned for my block (prefix)  so its a potential gotcha.

          I managed to work around it by updating my SPF record to specifically include a v6 address.

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          • johnpozJ
            johnpoz LAYER 8 Global Moderator
            last edited by

            SPF is not the same as a PTR, and how would that solve your problem when you just stated that gmail doesn't accept email from servers that don't have PTR.

            "FYI - google won't accept email via smtp over IPv6 if you don't have a reverse DNS v6 record for your mailserver's v6 address."

            You stated that spf is not sufficient - now your saying it is?

            "Having a valid SPF record with IPv6 included isn't sufficient."
            "I managed to work around it by updating my SPF record to specifically include a v6 address."

            If your isp supplies you with a /64 then they should provide the the ability to update your own ptr.  Hurricane electric allows for this with the /48 or /64s they give you for free.

            Who is your isp?

            An intelligent man is sometimes forced to be drunk to spend time with his fools
            If you get confused: Listen to the Music Play
            Please don't Chat/PM me for help, unless mod related
            SG-4860 24.11 | Lab VMs 2.8, 24.11

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