Master Exchange 2007

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Setting up a rDNS / PTR record for your mail server

Posted by shauncroucher on August 11, 2009

Some servers will check that you have a valid PTR or Reverse DNS record established for the IP address you are using to connect to the receiving SMTP server.

The reverse DNS (rDNS PTR) record is configured by the people who issued your IP address in most instances (so your ISP).

Below are two articles which explain the general requirements for reverse dns (rDNSPTR) records for your IP address.

I try to adhere to the following when setting up a rDNS (PTR) record:

Be a Fully Qualified Domain Name (FQDN) such as (not just ‘‘ or ‘server’).
Should not contain ‘in-addr-arpa’ and should not include words like pool or dyn etc.
Should match what you use in your SMTP HELOEHLO hostname (as some mail servers will check that the IP address of the SMTP TCP session matches who you say you are in your EHLO statement).

For neatness and as a good rule of thumb, if your incoming mail is delivered to the same server that you use for Outgoing you should make sure all the following FQDN’s match:

MX record
rDNS (PTR) record
SMTP EHLO hostname (Courtesy of Experts Exchange member Mestha)


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