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outlook error

Outlook 550 5.7.515 — Authentication Level Rejection

Microsoft rejected the message because the domain in the visible From identity did not meet the authentication level required for high-volume sending to Microsoft consumer mailboxes.

Diagnose your exact bounce Email Infrastructure Digital Twin

Most common causes

  • SPF does not pass for the sending path
  • DKIM is missing or does not pass
  • A DMARC record is missing or validation does not pass
  • The visible From identity is not aligned with the authentication path used for DMARC

What to verify next

  1. Inspect the NDR and message authentication headers
  2. Map sender infrastructure for the affected domain
  3. Verify both SPF and DKIM for high-volume Outlook.com sending
  4. Confirm DMARC publication and alignment with the visible From domain

Best diagnostic path

Live analysis

Mail Failure Doctor

Classify the complete rejection and preserve provider-specific diagnostic context.

Open analysis → Live analysis

Email Infrastructure Digital Twin

Map the domain’s public mail infrastructure and provider relationships before remediation.

Open analysis →

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 Microsoft: Fix NDR error 550 5.7.515.