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554 5.7.9: Message not accepted for policy reasons (Yahoo)

Yahoo refused the message for a policy reason, most often a DMARC failure on a domain with p=reject.

Bounce type
Hard bounce (permanent)
What to do
Fix your setup, keep the contact
Returned by
Yahoo / AOL

What 554 5.7.9 means

Yahoo returns 554 5.7.9 'Message not accepted for policy reasons' when a message breaks one of its filtering, authentication or anti-abuse rules. Yahoo's own help article ties it to DMARC: the From domain publishes p=reject and the message didn't pass, often because it was forwarded.

Yahoo's sender guidance says permanent 5xx errors should not be retried. Fix the cause, then send a new message.

What the bounce looks like

The wording providers document for this code. Your bounce may add an IP address, a session ID or a help link after it.

Yahoo
554 5.7.9 Message not accepted for policy reasons.

Why cold emailers see 554 5.7.9

  • DMARC failure on a domain with p=reject: SPF and DKIM didn't align with the From domain.
  • Mail forwarded through another server that broke SPF, without a valid DKIM signature to fall back on.
  • Poor sender reputation or content that matches Yahoo's spam rules.

How to fix 554 5.7.9

  1. Confirm SPF, DKIM and DMARC all pass with alignment for your From domain.
  2. Make sure DKIM signs with your own domain, so DMARC survives forwarding.
  3. Since February 2024 Yahoo requires bulk senders to authenticate with SPF and DKIM and publish DMARC, so fix those first.
  4. If authentication passes, look at reputation: complaint rate, list quality and volume.

Retry or suppress?

Don't suppress the recipient over a policy rejection; fix authentication and resend. Don't retry the same message unchanged.

Reading the code

The basic code 554 means "Transaction failed (permanent)" under RFC 5321. In 5.7.9, the 5 is the class (permanent failure) and the 7 is the subject (security or policy). The detail number 9 is registered in RFC 3463 / the IANA registry as "Authentication mechanism is too weak".

Class 5
Permanent failure
Resending the same message won't work. Something about the message, the recipient or the sender has to change first.
Subject 7
Security or policy
A security or policy decision: spam filtering, authentication, blocklists, permissions.
Detail 5.7.9
Authentication mechanism is too weak

Check the rest of your setup

Run your sending domain through the SPF, DKIM & DMARC checker to see which record fails, then follow how to set up SPF, DKIM and DMARC. Paste the headers of a test message into the email header analyzer to confirm all three pass.

Got a different bounce? Paste it into the SMTP error code lookup to decode it.

FAQ

Is 554 5.7.9 a hard bounce or a soft bounce?

554 5.7.9 is a permanent failure (a hard bounce): the receiving server won't accept this message if you send it again unchanged. But the cause is not the recipient's address, so treat it differently from a 'user unknown' bounce.

Should I remove the contact after a 554 5.7.9 bounce?

No. Don't suppress the recipient over a policy rejection; fix authentication and resend. Don't retry the same message unchanged.

What does 5.7.9 mean in the error code?

In 5.7.9, the 5 is the class (permanent failure) and the 7 is the subject (security or policy). The detail number 9 is registered in RFC 3463 / the IANA registry as "Authentication mechanism is too weak".

Related SMTP codes

See all SMTP error codes

Sources

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Clement reads the bounces that land in your Gmail and SMTP inboxes and tells dead addresses apart from policy blocks: it suppresses the first across every campaign and keeps the contact on the second, so you don't have to decode bounces by hand.

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