Yahoo / AOL "553 5.7.2 [TSS09] All messages from ... will be permanently deferred" and DMARC rejections: how to fix

What's happening: Yahoo and AOL (same mail system) refused or deferred your message. Since February 2024 Yahoo requires every sender to pass SPF or DKIM, and bulk senders to pass DMARC with alignment and offer one-click unsubscribe. A 553 5.7.2 or a 554 5.7.9 Message not accepted for policy reasons usually means authentication failed or the From domain's DMARC policy told Yahoo to reject.

How to fix it

  1. Check that SPF or DKIM passes and aligns with the domain in your From address. Mail sent through a newsletter or CRM tool often signs with the tool's domain, which fails DMARC.
  2. Set up DKIM for your own domain in every tool that sends as you (Google Workspace, Microsoft 365, Mailchimp, SendGrid and others each have a DKIM step).
  3. Publish a DMARC record if you have none: start with v=DMARC1; p=none; rua=mailto:you@yourdomain.com.
  4. If you send in bulk, add a List-Unsubscribe header with one-click (RFC 8058) support and keep spam complaints under 0.3%.
  5. If the error mentions TSS04 or a deferral, slow down: Yahoo rate-limits new or low-reputation senders. Retry gradually instead of resending everything at once.

Not sure which record is wrong? Check your domain free: it shows which of SPF, DKIM and DMARC is failing, in 5 seconds, no signup.

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