What reverse DNS (PTR) records are#
A PTR record maps a sending IP address back to a hostname. Mailbox providers check that the PTR resolves and that the hostname's A record points back to the same IP (forward-confirmed reverse DNS).
Why it matters#
Gmail's sender guidelines require valid forward and reverse DNS. Missing or generic PTRs are a classic spam signal and cause outright rejections at many gateways.
Getting started#
- Ask your hosting or ESP provider to set a PTR for each sending IP.
- Use a hostname under your domain (mail1.example.com) rather than the provider's generic name.
- Create the matching A record so forward and reverse agree.
- Use the same hostname in the SMTP HELO/EHLO banner.
Common mistakes#
- Generic PTRs like 203-0-113-10.provider.net.
- HELO names that do not match the PTR.
Frequently asked questions#
Can I set PTR records in my own DNS?
No. PTRs live in the IP owner's reverse zone. Your hosting provider or ESP sets them, though some offer self-service.