Reverse DNS

By | November 4, 2016

Reverse DNS or rDNS is one of the older methods used to verify an email was sent from the domain. It is a record created by the ISP and not the DNS records associated with the domain. It should be setup anytime an ISP is added or changed. Each ISP has their own way of setting these up from sending an email to particular address (sent from the client domain not ours) to calling support. This should be done before email starts going out from the new IP to prevent NDRs. To set up a reverse DNS record:

  1. Verify email is not going out through our spam filter. If so then stop here.
  2. Verify the outbound IP by using on the email server.
  3. Find the Masquerade Domain the Exchange server uses when sending email. The NMS standard is
  4. Contact the ISP and have them set up the rDNS record.
  5. Verify it is in place by testing the IP at

e.g. result for reverse-dns