How do I check if my domain’s PTR (Reverse DNS) record is set up correctly?

A PTR record check is run by performing a reverse IP lookup on your mail server’s IP address to verify that it resolves back to your primary sending domain.

“This is a quick diagnostic, running the reverse lookup to confirm your mail server’s IP actually resolves back to your domain. I’ll check it and fix it if it’s off within 24 hours for $99.”
— Jeff Bollettino, Managing Director, Ignite Conversions