What DMARC policy should I start with on Postmark domains?

Start with p=none to collect reports without blocking anything. Move to quarantine and reject only when SPF and DKIM alignment look healthy.

Where do I publish the DMARC record?

DMARC is a TXT record at _dmarc.yourdomain.com. It should start with v=DMARC1 and include a p= policy.

Why does DMARC fail even when SPF and DKIM pass?

DMARC cares about alignment. The domain in the visible From header must align with the domain authenticated by SPF or DKIM.

How to set up DMARC on Postmark

Step by step DMARC setup for Postmark: complete instructions, examples, verification commands, and common pitfalls.

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This is a reference guide for configuring DMARC on Postmark. Use it while editing DNS or when troubleshooting deliverability.

Tip: Avoid common mistakes: follow these steps to add DMARC on Postmark. Then verify everything with the InboxGreen Free Checker.

Provider-specific notes for Postmark

Postmark uses Sender Signatures, not domain-level DKIM by default. Each sender signature domain gets its own DKIM record published by Postmark.
Postmark DKIM keys rotate periodically. If DKIM suddenly fails, check the Postmark dashboard for an updated record value.
Postmark → Sender Signatures → Domain → DKIM.

DMARC policy ladder

DMARC connects SPF and DKIM to the visible From domain. The safe approach is to start in monitoring, fix alignment issues, then gradually move to stricter policies.

Stage	TXT value	When to use it
Monitor	`v=DMARC1; p=none; rua=mailto:[email protected]; fo=1`	Collect reports and understand who sends on your behalf.
Quarantine	`v=DMARC1; p=quarantine; pct=25; rua=mailto:[email protected]; fo=1`	Quarantine a portion of failing mail. Raise `pct` as confidence grows.
Reject	`v=DMARC1; p=reject; pct=100; rua=mailto:[email protected]; fo=1`	Full protection once alignment is good and monitored.

Publish DMARC

Create a TXT record at host _dmarc with your chosen value.
Make sure the rua address exists and can receive XML reports.

Verify and troubleshoot

dig TXT _dmarc.yourdomain.com +short
nslookup -type=txt _dmarc.yourdomain.com

Check that either SPF or DKIM aligns with the visible From domain.
Debug failing sources before moving beyond p=none.

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