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Received the following error from a user:
WARNING: Forward-DNS does NOT match Reverse-DNS. DNS is INCONSISTENT.

Some users are having their email marked as spam. I looked in the PTR records and found the following information:
70.63.x.34 PTR - mail.x.com
70.63.x.36 PTR - mail.x.com

x.com
A record - mail.x.com -> 70.63.x.36

I guess my question would be; Should I remove the PTR from 70.63.x.34?

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Doing a dig -t mx x.com. shows that the mx record points to mail.x.com –  evolvd May 24 '11 at 16:27
    
but from which ip are you sending from? –  David Schmitt May 24 '11 at 16:31
    
I looked at a header from a email that a client sent me and it shows that it is coming from 70.63.x.36 –  evolvd May 24 '11 at 18:02

4 Answers 4

up vote 2 down vote accepted

Yes, If you have no A record for mail.x.com set to 70.63.x.34. The recipient's email system likely has a spam filter that does reverse lookups on the sender's domain to help mark spam.

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Also, what is your server configured to say for the EHLO command? If you are reporting your internal server, it will not match.

In Exchange 2007/2010, you would go to Organization Configuration>Hub Transport>Send Connectors and on the General Tab in the "Specify the FQND this connector will provide in response to HELO or EHLO" field, enter that mail.x.com.

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If you send mail from .36 you shouldn't have a problem. If you send from .34 you will have a problem, or if you send from both, you need both addresses as A records and both as PTR records and maybe as SPF records too!

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You haven't said how the mail server is actually configured to send mail which is the key bit.

Having an extra PTR record is not a problem. Sending mail from that IP is.

Try this:

dig -t mx x.com.
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mx points to mail.x.com –  evolvd May 24 '11 at 16:27
    
Then your .34 IP is not an issue. –  dmourati May 24 '11 at 18:17

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