Updating DNS reverse look up on Exchange?

By eheraldez ·
My Company has a report server that generates event reports for our customers, and some prefer that they receive their report in the form of SMS on their cellphone. For the past couple weeks customers with At&t as their carrier have stopped receiving messages. A talk with At&t confirms that the messages aren't getting filtered as spam and dropped because the reverse look up is failing. An nslookup points me to our exchange servers internal IP. I'm assuming I need to update our reverse look up record.

Our report server uses Outlook express that's connected to Exchange 2003 sitting behind an Astaro firewall. The public IP we have assigned for exchange is 123.456.7.8 (changed for the sake of example) and internally (also changed)

Thanks in advance as it will be a huge relief to have this issue resolved.


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Reverse DNS / sending server

by Churdoo In reply to Updating DNS reverse look ...

Reverse DNS is generally managed by the ISP that's providing your connectivity, as they likely are authoritive for the IP-block that your Public IP falls within.

You'll have to contact your ISP and see if they will create/update the PTR record for the IP through which your exchange server sends outbound SMTP (likely your public IP), and the PTR record should return the FQDN supplied by your exchange server at HELO/EHLO. In Exchange 2003 this FQDN is found in the SMTP virtual server properties / Delivery tab / Advanced / FQDN. Further, a FORWARD lookup of this same FQDN should yield the same IP.

If for some reason your ISP is not able to make this Reverse DNS entry for you, all is not necessarily lost. You can have your exchange server Smart-Host through an SMTP server/service that is properly identified and compliant with current anti-spam best practices.

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to add to Churdoo's suggestion ......

by CG IT In reply to Reverse DNS / sending ser ...

Many email servers require reverse DNS lookup as part of their spam filtering. If you do not host your email server and the DNS server that resolves names to address, then whomever does should have reverse DNS enabled. If not, or it's an extra pay service, you'll have to pay for the reverse DNS lookup service.

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Thanks for you help...

by eheraldez In reply to to add to Churdoo's sugge ...

Hey everybody thanks for all your help. I got a hold of our primary isp and they verified we already had a reverse look up record. At&t was of no help in resolving this issue. Considering the time frame I had to work with I went the hosting service route and set everything up today. So far I've had no issues.

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