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I am a bit confused about PTR records and how to set it up correctly.

This is the current setup:

A website: domain.com, on this website I have a mailaddress [email protected]. On domain.com I have an iframe which shows a questionaire, this questionaire is hosted on otherdomain.com.

At some point in the questionaire users will get a confirmation mail from the sender [email protected] which is sent from a mailserver at smtp.otherdomain.com.

  • On domain.com I have added the IP for smtp.otherdomain.com in my SPF record.
  • On domain.com I have a PTR record set to the IP of the server it is hosted on
  • On otherdomain.com there is a PTR record set to smtp.otherdomain.com

In most cases sending mails goes fine, however last week I got this message: 550 inconsistent or no DNS PTR record for << The IP of otherdomain.com >>

The mails did not end up in the inbox of '@freenet.de' mail accounts.

How can I fix this?

1 Answer 1

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@Gerb You are trying to send out mail from [email protected] through smtp.otherdomain.com. To make sure your mails work, you only require the following.

  • SPF record allowing smtp.otherdomain.com as allowed sender (which you already did)
  • PTR record for sending server smtp.otherdomain.com (if the IP of smtp.otherdomain.com is 111.222.111.222 then there should be a PTR record for 111.222.111.222 pointing to smtp.otherdomain.com/)

Note

  • Please note that if you have multiple IPs using which smtp.otherdomain.com server sends out emails, there should be PTRs for all IPs.
  • Here smtp.otherdomain.com is the name of your mailserver. (for eg. myhostname of postfix or content of /var/qmail/me in qmail)
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  • Just to be completely sure. The PTR records only need to be on the otherdomain.com, correct?
    – Gerb
    Aug 6, 2013 at 11:43
  • No the PTR record should be the name of the mail server, Please see the note section of the answer.
    – clement
    Aug 6, 2013 at 12:10
  • The in A and ptr must match the mx record of the domain. meaning : if your domain1.com has mx.mailer.com as mx so mx.mailer.com must match the aame ip in forward (in A) and reverse (ptr) to the same ip that its not regionized as spam
    – djdomi
    Jun 9, 2020 at 14:28

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