Gmail DMARC policy rejection

Gmail 550 5.7.40: Your message was blocked because the sending domain doesn't have a DMARC record or policy

Gmail can report a policy requirement when a sending domain has no applicable DMARC policy. Confirm the current policy through a bounded RFC 9989 DNS tree walk before publishing or changing a record.

Problem description

Gmail rejects mail from your domain with the following error message:

550 5.7.40 Your message was blocked because the sending domain doesn't have a DMARC record or the DMARC record doesn't specify a DMARC policy.

Run this automated test on my domain

Enter your domain. MailFixIt checks the relevant DNS records automatically and shows the evidence.

Is this temporary or permanent?

550 is permanent for this delivery attempt. Publish or correct the applicable policy, verify the sending identities, and then send a new message.

What the check distinguishes

Missing policy: the full bounded tree walk found no applicable DMARC record.
Invalid policy: a candidate record exists but cannot be applied safely.
Temporary DNS result: policy absence is unknown, so the checker does not recommend publishing over an unverified state.
Valid policy: public DNS has a policy, but that alone does not prove a particular message is aligned.

Safe policy workflow

Confirm every legitimate sender and its aligned SPF or DKIM configuration.
Publish a valid monitoring policy first when the domain has no policy.
Use reports and fresh message headers to verify legitimate traffic before moving to enforcement.
Select p=quarantine or p=reject only after verified alignment; neither is a universal repair for a delivery problem.

Frequently asked questions

What does Gmail 550 5.7.40 mean?

It is a Gmail receiver-reported policy requirement. Verify current DMARC discovery first: a missing or invalid policy can be diagnosed from DNS, while a temporary lookup result cannot confirm absence.

Will publishing DMARC guarantee delivery?

No. A valid DMARC policy does not prove SPF or DKIM alignment for a particular message, inbox placement, or recipient-specific acceptance.

Related email diagnostics

DMARC policy for the visible From subdomain is unexpectedFind the effective DMARC policy for a visible From subdomain. See whether p, sp, np or test mode applies before changing DMARC DNS. DMARC reports not received: External report destination is not authorizedFind why DMARC aggregate reports are not arriving. Check external reporting authorization in DNS, understand the limits, and verify a safe fix.

Primary sources: Gmail SMTP errors, RFC 9989 DMARC.