What the bounce says
Exact wording as it appears in the rejection or NDR. Placeholders such as x.x.x.x and example.com stand for your own address and domain.
554 5.7.9: Message not accepted for policy reasons. See https://postmaster.yahooinc.com/error-codes 554 5.7.9 Message not accepted for policy reasons
Yahoo enforces DMARC strictly, including for its own domain. 554 5.7.9 means the message failed the DMARC policy of the From domain and that policy asked for rejection. The most frequent case is a yahoo.com address used as From on a non-Yahoo server.
Most common causes
- Sending with a yahoo.com From address from a third-party server (Yahoo enforces p=reject)
- The From domain publishes p=reject and the message did not align
- A mailing list forwarded mail from an enforcing domain without rewriting From
- DKIM broke in transit
What to verify next
- Do not send from yahoo.com addresses through other services; use your own domain
- Test DMARC alignment for the real sending path
- For lists, rewrite From or use ARC-aware forwarding
- Inspect Authentication-Results on a delivered copy
Yahoo’s own domain is p=reject
Since 2014 yahoo.com publishes a reject policy. Any message with a yahoo.com From address that does not come from Yahoo’s infrastructure fails alignment and is rejected by every receiver that honours DMARC — including Yahoo itself. Forms, CRMs and newsletters that set From to a user’s Yahoo address hit this constantly.
The fix is to send from a domain you control and put the Yahoo address in Reply-To.
- yahoo.com is p=reject.
- Never use a Yahoo address as From on other infrastructure.
- Use your own domain; put the Yahoo address in Reply-To.
Your own domain at reject
If the From domain is yours and enforces reject, the message lacked an aligned path. Configure a custom bounce domain or DKIM signing for the platform and verify with a test message.
Lists and forwarding
Mailing lists that preserve the original From break DMARC for enforcing domains. Rewrite From to the list’s domain, or use ARC and hope the receiver trusts the list.
Best diagnostic path
Mail Failure Doctor
Classify the complete rejection and preserve provider-specific diagnostic context.
Open analysis → Live analysisDMARC Alignment Lab
Compare visible From, envelope sender and DKIM identities without reducing the result to a pass/fail label.
Open analysis → Live analysisEmail Infrastructure Digital Twin
Map the domain’s public mail infrastructure and provider relationships before remediation.
Open analysis →Known limits
- Yahoo applies DMARC without exceptions for lists.
- The rejection does not name which mechanism failed; read a delivered copy’s headers.
Common questions
I send from my Yahoo address through my website.
That is exactly the case Yahoo rejects. Send from your website’s domain with Reply-To set to the Yahoo address.
Does p=quarantine avoid this?
Quarantine would land in spam rather than reject. Yahoo’s own domain is reject; for your domain, fix alignment rather than weakening policy.
Why did Gmail accept it?
Receivers may apply local overrides. Yahoo enforces the published policy.
Why the exact message matters
The same status family can be triggered by different conditions, and providers frequently add diagnostic text that narrows the issue. Use the complete rejection text rather than treating the numeric code as a complete diagnosis.
Provider reference
For the provider-defined meaning and current requirements, review Yahoo Sender Hub SMTP error codes.