How to match PTR record with a different domain?

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?


@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)