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Gmail

550 5.7.40 “doesn't have a DMARC record”

Gmail requires bulk senders to publish a DMARC record with a policy. Your domain has none, or its record names no policy. Google's own pages list the temporary code as both 4.7.40 and 4.7.31.

Codes: 550 5.7.40 or 421 4.7.40. Source: Google Workspace: Gmail SMTP errors and codes.

What usually causes it

  • No TXT record at _dmarc.<your domain>.
  • A record that doesn't start with v=DMARC1; p=..., which Google requires as its first two tags.

How to fix it

  • Publish a TXT record at _dmarc.<your domain>: v=DMARC1; p=none; rua=mailto:<an address you read>.
  • Let SPF and DKIM run for a couple of days first, then tighten p=none to quarantine or reject once the reports show only your own services.
The free email check can find this

The free check shows whether a DMARC record exists, whether it has a policy, and where its reports go.

Run the free email check

Want it fixed? Our email deliverability packages start at $49 for an audit and plan. Other error codes.