What is a PTR record, and why do you need one when sending emails

A PTR is a reverse lookup record in the DNS server that returns a hostname for a given IP address. It is the opposite of an A record, which resolves a hostname to an IP.

Consider the following example:

  • You run the following command from any computer to get the IP address for www.synametrics.com
    nslookup www.synametrics.com
  • This should return
  • You run the following command to get a hostname back from the IP:
    nslookup -q=ptr
    This should return www.synametrics.com back again.

A PTR record is vital for a successful email delivery. Without this entry, your emails will be treated as junk.

Adding a PTR Record

A PTR record goes into the ISP's DNS server, which owns the IP address. For example, if you get an IP address from Verizon FIOS, this record goes into Verizon's DNS server, not yours. Therefore, you must ask your ISP to associate a name to this IP. ISP typically will only add a PTR record if you have a static IP address. They will not do it for a dynamic IP.

How To Validate Your PTR Record

Use the following steps if you're using Xeams:

  • Log in as the administrator
  • Click Tools/Diagnostic Check Outbound
  • Select a domain and click Submit

Use the following steps if you're not using Xeams:

  • Compose an email to validate.server@synametrics.com with the word validate in the subject line.
  • An automatically generated email will be sent to you in reply containing a report.