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Exchange 2010 reverse DNS not working

We currently have two networks running on two separate IP address spaces. We had to move our exchange server from one to the other. Now we are getting failed reverse DNS lookup NDRs.

Our MX records are showing the correct IP address, when I ping the mail server from outside the network the correct IP address shows up. However, when I use mxtoolbox.com's smtp tester I get the error that SMTP reverse banner check is failing and we are getting numerous NDRs due to lack of reverse DNS.

What am I missing?

Please let me know what information I need to provide to help you solve this issue.
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Byrdpire
Asked:
Byrdpire
2 Solutions
 
Naushad shaikhIT Consultant - Messaging SupportCommented:
have you created PTR record on your external DNS contact your ISP and make sure reverse DNS setup correctly
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Alan HardistyCo-OwnerCommented:
MX Toolbox gives a false report for Exchange 2007 / 2010 / 2013, so ignore that.

Reverse DNS is something setup on your IP Address.

From a command prompt you can see what is set on the IP Address:

nslookup <IP_Address> (e.g., nslookup 123.123.123.123)

That should tell you what is set as reverse DNS.

If nothing is set, call your ISP and ask them to add it, but make sure you have an A record pointing to the same IP Address or they won't add it e.g., mail.yourdomain.com

Alan
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Simon Butler (Sembee)ConsultantCommented:
If you are using the same firewall, it could be the NAT is wrong, so you are going out on the wrong IP address.

Simon.
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ByrdpireAuthor Commented:
Thanks guys, I've never had to do this before, didn't realize my old boss had setup originally and we've just been using it.

I gave AT&T a call and they were happy to help add a reverse PTR for our IP address, contrary to what I had read on the internet.
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