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Re: myhostname and PTR

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  • Noel Jones
    ... Ideally, the PTR, A record, and HELO hostname should all agree. ... There doesn t appear to be a matching A record for that PTR, so the setup is
    Message 1 of 5 , Jun 21, 2013
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      On 6/21/2013 10:24 AM, Titanus Eramius wrote:
      > Hello
      >
      > I've searched several times about information on the PTR record, and
      > what myhostname in main.cf should be. The problem is not the
      > information, but the fact that I struggle to understand it...

      Ideally, the PTR, A record, and HELO hostname should all agree.

      >
      > This server runs with the IP address 46.21.105.38 from a hosted VPS, and
      > using dig to do a reverse lookup gives
      > 46-21-105-38-static.serverhotell.net.

      There doesn't appear to be a matching A record for that PTR, so the
      setup is incomplete. Postfix will label such a host as "unknown".
      Most sites (but not all!) will still accept your mail.

      Best to request your hosting company to give you a custom PTR with
      your domain name, something like smtp.example.com, mx1.example.com,
      mail.example.com, etc. so your server looks like a mail server and
      not a random infected bot. If this host handles several domains,
      just pick one for the PTR and A record. No need to list them all.

      Whatever PTR you end up with, there should be a matching A record
      with the server address.

      >
      > Does this means I should use 46-21-105-38-static as myhostname?

      While technically correct to use the
      46-21-105-38-static.serverhotell.net hostname, that's the same name
      a random infected bot will use and should be avoided.

      I would still suggest a myhostname setting that makes you look like
      a mail server instead of a random bot, even if it doesn't match the
      PTR. Make sure you also have an A record set for the hostname that
      points back to your server's IP.




      -- Noel Jones
    • Titanus Eramius
      Thank you for the replys, they are very helpful. I own this domain, and the danish handler of .dk allows all settings in DNS to be altered, but the hosting
      Message 2 of 5 , Jun 22, 2013
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        Thank you for the replys, they are very helpful.

        I "own" this domain, and the danish handler of .dk allows all settings
        in DNS to be altered, but the hosting provider does not. All records
        besides PTR is within my control at the provider, so I guess it's a
        design decision they have taken, and I will contact them about this.


        Cheers
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