How do you verify reverse DNS (PTR) alignment for bounce analysis?

PTR alignment affects deliverability and diagnostics:

What PTR is:

Reverse DNS maps IP to hostname. PTR record published by IP owner. Used for sender verification.

Alignment check:

Look up PTR for your sending IP. Then forward resolve that hostname. Should return the original IP. This is Forward-Confirmed Reverse DNS (FCrDNS).

Testing commands:

dig -x 192.0.2.1: Get PTR record. dig A hostname.example.com: Forward resolve result. Compare IPs.

Why it matters:

Some receivers reject without valid PTR. Helps establish sender legitimacy. Part of basic email hygiene.

Common issues:

No PTR record configured. PTR does not forward resolve. Hostname too generic.

PTR alignment is your ship's registration matching its name. Essential for credibility at many ports.