rDNS lookup failing for emails sent to aol.com, charter.net, att.net

Hello all! We recently migrated to a new server and reinstalled SmarterMail. All of our firewall and DNS settings were transferred over from the old setup, and the only thing that changed was our IP address block. Since the reinstall of SM, we have received a lot of rDNS lookup failures from multiple domains.

We have spoken to our ISP, our web server host, and tried to bring in AOL on this. Our ISP told us that everything is fine on thier end, AOL gave us this link http://postmaster.aol.com/cgi-bin/plugh/rdns.pl to check our DNS and it matches our domain correctly, and our web host found a missing PTR record that has now been added.

Are there any settings in SM that could be causing this? Our hostname and DNS IPs match up with what they should be. I can post the headers for the failures if needed. Thanks

Bruce Barnes Replied

12/11/2014 at 11:16 AM

RDNS must be added by the IP provider for your network. In a hosted situation, then you contact your hosting company to map the RDNs. PTR records and RDNS are not the same thing. Remember, too, that CNAMES are PROHIBITED for all MX records. They must point directly to a hostname/IP address combination.

Bruce Barnes ChicagoNetTech Inc brucecnt@comcast.net Phonr: (773) 491-9019 Phone: (224) 444-0169 E-Mail and DNS Security Specialist Network Security Specialist Customer Service Portal: https://portal.chicagonettech.com Website: https://www.ChicagoNetTech.com Security Blog: http://networkbastion.blogspot.com/ Web and E-Mail Hosting, E-Mail Security and Consulting

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