Multiple A records and reverse DNS

Matus UHLAR - fantomas uhlar at
Thu Mar 17 17:13:06 UTC 2016

On 17.03.16 09:53, Thomas Schulz wrote:
>This is not a BIND question but I hope people here will know the answer.
>We are switching service providers and I understand that many email SPAM
>prevention systems insist on the reverse DNS matching the forward DNS.
>If I have two A records for our mail server and the reverse record matches
>one of them, will that be good enough. Or will the fact that the other A
>record does not match cause trouble.

Reverse DNS is only important for mailserver that connects to outside, no
for receiving servers or MX records.

If the mail server connects outside, it's IP address is checked by many
receiving mailservers or spam filters for reverse DNS and the resolved name
has to point to that IP address

Invalid reverse DNS is often worse than no reverse at all...

... I have met complaints noting that recipients mail servers' IP is
checked, or that rDNS must point to the MX content. They were all wrong, the
problem usually lied in blacklist, invalid mailserver configuration etc...

No sane admin or software will check reverse DNS of mailserver they are
connecting to or MX records they send mail to. 
They would block out services like gmail, yahoo, aol, without any valid

Matus UHLAR - fantomas, uhlar at ;
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