Outlook 550 5.7.515: domain does not meet the required authentication level

What the bounce means and the exact steps to stop it.

The bounce looks like this
550 5.7.515 Access denied, sending domain yourdomain.com does not meet the required authentication level.

What it means

Since May 2025 Outlook.com, Hotmail and Live addresses reject mail from domains that send them 5,000+ messages a day unless SPF passes, DKIM passes and DMARC is published (at least p=none) and aligned with SPF or DKIM.

How to fix it

  1. Run the checker for the domain in your From address – SPF, DKIM and DMARC all need to be green.
  2. Add every sending service to SPF (SPF generator) and enable DKIM with your own domain in each of them.
  3. Publish DMARC (DMARC generator) with a report address, then watch the reports for senders you forgot.
  4. Forwarded mail can break DKIM: if the bounce comes after a forward, fix authentication at the original sender.

Check your domain now

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