What is a PTR (Pointer) record?

A PTR record (Pointer record) provides reverse DNS lookup:

Structure: IP address (in reverse format) → hostname

1.2.0.192.in-addr.arpa PTR mail.tidalmail.com

Who controls PTR records: The IP address owner (usually your hosting provider or ISP) manages PTR records, not your domain registrar.

Setting up: Contact your IP provider to create or modify PTR records for your sending IPs.

Email requirements:

PTR should exist for every sending IP

Hostname should be meaningful (not generic)

Forward lookup of that hostname should return the same IP (FCrDNS)

The reverse registry lookup. Given a hull number, return the ship's registered name.