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I have site and I want to set an external mail server , most whitelists like AOL requires reverse DNS for all IPs, but in order to fetch the bounces properly I will be sending mail like this, return path and from being different domains:

return-path from:

So I am unsure if the reverse DNS of m1 IP should match the or just

Thank you.

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I will. Thanks for the tip, I am kind of new. – adrianTNT Sep 30 '11 at 22:24

3 Answers 3

up vote 3 down vote accepted

Receiving mail servers check none, one, many or all of the following:

  1. Is the HELO name equal to the hostname (A record)?
  2. Is PTR of the IP equal to the A record of the hostname (hostname ==(PTR)==> IP ==(A)==> hostname)?
  3. Is the IP part of the provided SPF record?
  4. Does the sender's domain have at least one MX record? Which doesn't have to match IP/hostname.

Receiving mail servers that check if the sending server is also the MX server are badly configured and should be eliminated from the Internet.

Same goes for servers that check if the hostname is equal to the domain name of the mail. Look at Google where you can send mail with (almost) any domain whereas their hostname always contains

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While looking at AOL whitelisting application they mentioned that only IPs with rDNS will be accepted and I assumed that the rDNS of all IPs should match the "From" domain, this is wrong, right? – adrianTNT Sep 30 '11 at 22:29
@adrianTNT Yes, this is wrong. The rDNS should match the hostname. – mailq Sep 30 '11 at 22:33

The reverse DNS should point to the mailserver's hostname ie

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Your RDNS needs to match the from line and your servername on ECHO remember to add an SPF record as that is important also. Your Return Path shouldn't get RDNS checked aslong as RDNS for you domain is valid.

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