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Permanent failure

550 5.7.515 Outlook.com: authentication level not met

Quick answer

Outlook.com rejected the message because the sending domain does not meet Microsoft's authentication requirements for high-volume senders: SPF, DKIM and DMARC must pass for domains sending over 5,000 messages a day to Outlook.com, Hotmail and Live addresses. The rules took effect on May 5, 2025: non-compliant mail is routed to Junk first and can be rejected with this code.

Recommended action: Fix sender reputation

Common causes

  • DKIM signing is not set up for the From domain.
  • No DMARC record, or SPF and DKIM do not align with the From domain.
  • A newly added sending service that is not in the SPF record and does not sign with your domain.

What to do

Publish SPF covering every sender, sign with DKIM using your own domain, and publish a DMARC record of at least p=none that aligns with SPF or DKIM. Verify with our DMARC Checker and resend. The recipient addresses are not at fault.

Provider note: This code only appears on mail you send. RocketVerifier never sends a message, and if Microsoft refuses a verification probe for policy reasons, the result is unknown and free, never undeliverable.

How to read 550 5.7.515

550 is the basic SMTP reply defined in RFC 5321. 5.7.515 is the enhanced status code from RFC 3463, which reads as class, subject and detail:

Class
5Permanent failure
Subject
.7Security or policy
Detail
.515Outlook.com: authentication level not met

Further reading

FAQ

Frequently asked questions

Does 550 5.7.515 apply to Microsoft 365 business recipients?

Microsoft's announcement covers Outlook.com, its consumer service. Microsoft 365 tenants apply their own filtering and authentication checks.

I send fewer than 5,000 messages a day. Can I still get 5.7.515?

The requirement targets high-volume senders, but Microsoft recommends the same authentication for everyone, and unauthenticated mail at any volume is more likely to be filtered.

Related bounce codes

All bounce codes

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