550 5.7.26: rejected under the sender's DMARC policy
Gmail rejected the message because it failed DMARC, and the From domain's DMARC policy tells receivers to refuse mail that fails.
- Gmail
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 550 5.7.26
- Provider
- Gmail and Google Workspace
- Temporary or permanent
- PermanentRefused for good: the message comes back to the sender, and resending it gets the same answer.
- Who has to act
- The sender. The fix is on the sending side: your domain, your server or your list.
- What the server says
550 5.7.26 …is not accepted due to domain's DMARC policy.
What it means
The domain in the From address publishes a DMARC policy that asks receivers to reject mail failing authentication. This message did not pass SPF or DKIM in alignment with that domain, so Gmail followed the policy and refused it. Either a legitimate sending service for the domain is not set up for aligned SPF or DKIM, or someone else sent the message using the domain, which is what DMARC exists to stop. Mailing lists and forwarders that change messages are common legitimate casualties. Google's reply asks you to contact the domain's administrator if the mail was legitimate.
Common causes
- A sending service that signs DKIM with its own domain and uses its own envelope domain, so nothing aligns.
- A mailing list or forwarder that changes the message and breaks DKIM.
- Spoofed mail using the domain in From.
How to fix it
- 01Read the domain's DMARC aggregate reports to see which sources fail.
- 02Set up DKIM with your own domain at every legitimate sending service, or a custom Return-Path so SPF aligns.
- 03If the failing source is not yours, leave the policy in place.
- 04If legitimate mail fails while you fix the sources, consider p=quarantine or p=none for a while, then return to p=reject.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- Gmail SMTP errors and codes (Google Workspace Admin Help)knowledge.workspace.google.com
Related codes
- 451 4.7.26DMARC check hit a DNS failure.Gmail could not finish checking SPF and DKIM because a DNS lookup failed, and the From domain's DMARC policy says to reject mail that does not authenticate.
- 550 5.7.26Unauthenticated sender, blocked.Gmail rejected the message because it passed neither SPF nor DKIM, and Gmail requires every sender to pass at least one.
- 550Mailbox unavailable.The receiving server permanently refused the message for this recipient: the mailbox does not exist, cannot be reached, or the server rejected the message by policy.
- 550 5.7.26Multiple authentication checks failed.The message failed more than one authentication check, for example SPF and DKIM, and the receiving server's policy rejects it.
Further reading
All 108 Gmail codesEvery code in the wikiPaste your own bounce