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.
Mistake 1: Generic PTRs like 203-0-113-10.provider.net#
Why it hurts: this undermines reverse DNS (PTR) records at the point where mailbox providers make their decision, and it is rarely surfaced by your own tooling until placement drops.
Fix: Ask your hosting or ESP provider to set a PTR for each sending IP.
Mistake 2: HELO names that do not match the PTR#
Why it hurts: this undermines reverse DNS (PTR) records at the point where mailbox providers make their decision, and it is rarely surfaced by your own tooling until placement drops.
Fix: Use a hostname under your domain (mail1.example.com) rather than the provider's generic name.
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.