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reverse DNS question

Posted on 2008-10-21
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Last Modified: 2010-04-07
I have installed a Barracuda spam firewall to filter all of my *outbound* email from my mail server.  Because of this, I now have a DNS question.

The public ip address of my email server is 12.34.56.1 and that is associoated with mail.mydomain.com

All outbound email goes from the mail server first to the Barracuda & then out to the internet.  When the Barracuda sends out the mail, the email is identified as coming from 12.34.56.2

Some email messages have been rejected because some recipient's servers attempt a reverse dns lookup on 12.34.56.2 & there is no reverse dns  lookup for that ip.
 
I'm guessing a solution would be to add a "reverse DNS" entry for 12.34.56.2 - mail.mydomain.com

However, I'm worried - I don't want any mail to be sent back to 12.34.56.2 since that is an outbound device only.  I want mail to only come in on 12.34.56.1

Is adding this reverse DNS entry safe?
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Question by:brianp111
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by:MobiNet-ca
ID: 22767215

I would create a reverse DNS record such as "outbound.mydomain.com" and point it at 12.34.56.1 and leave the records for the real mail server alone.
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MobiNet-ca earned 1500 total points
ID: 22767223
Sorry that should have been the .2 IP

I would create a reverse DNS record such as "outbound.mydomain.com" and point it at 12.34.56.2 and leave the records for the real mail server alone.
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