550 5.7.515: Outlook Rejects Unauthenticated High-Volume Sender
The 550 5.7.515 bounce is Outlook.com rejecting a high-volume From domain that fails Microsoft's authentication bar: SPF and DKIM must pass, and the message must pass DMARC.
Published · Last verified · Maintained by TamingDNS
550
5.7.515
Outlook Rejects Unauthenticated High-Volume Sender
Very Common
🔢 Enhanced Status Code Breakdown: 5.7.515
| Component | Value | Meaning |
|---|---|---|
| Class | 5 | Permanent failure (Hard bounce) |
| Subject | 7 | Security or policy |
| Detail | 515 | Outlook Rejects Unauthenticated High-Volume Sender |
Per RFC 3463 Enhanced Mail System Status Codes. Class (X) = severity, Subject (Y) = category, Detail (Z) = specific condition.
💬 What This Error Means
Outlook.com rejected your email because your From domain did not meet the authentication level Microsoft sets for high-volume senders. The bar applies once you send 5,000 or more messages to Microsoft's consumer services (Outlook.com, Hotmail, Live.com, MSN) using the same From domain. Both SPF and DKIM must pass. You need a published DMARC record, at least p=none, and the message must pass DMARC, which needs SPF or DKIM to align with the From domain. Microsoft's NDR page for this code says the message was rejected.
Common Causes
- Your From domain sends 5,000 or more messages to Microsoft consumer mailboxes (Outlook.com, Hotmail, Live.com, MSN)
- SPF does not pass: the record is missing, broken, or does not authorise the sending IP
- DKIM does not pass: the signature is missing or fails verification
- No DMARC record is published, or the message fails DMARC because neither SPF nor DKIM aligns with the From domain
How to Fix This
- Publish a valid SPF record covering every service that sends as your domain
- Enable DKIM signing at your mail provider and publish the public key in DNS
- Publish a DMARC record at <code>_dmarc.yourdomain</code>, starting at <code>p=none</code> and moving towards <code>p=quarantine</code> or <code>p=reject</code>
- Make sure the From domain aligns with the domain that passes SPF or DKIM
- If a third-party service sends for you, check it uses your domain in the MAIL FROM address and signs DKIM with your domain
- Run our Domain Checker against your sending domain to confirm all three records pass and align
📚 Official Documentation
Microsoft's NDR page for 550 5.7.515 covers Outlook.com, Hotmail, Live.com and MSN. It applies once you send 5,000 or more messages using the same From domain. Both SPF and DKIM must pass, a DMARC record must be published, and the message must pass DMARC. Mail that falls short is rejected.
📖 Microsoft 365 / Outlook documentation → Browse all Microsoft 365 / Outlook error codes →📋 Real-World Example Messages
These are real bounce message formats you might receive. Paste yours into the Bounce Decoder for instant analysis.
550; 5.7.515 Access denied, sending domain [example.com] does not meet the required authentication level.
🔗 Related Error Codes
🔧 Related Diagnostic Tools
These tools can help you diagnose and fix this type of bounce:
🔧 This Bounce Is Related to Email Authentication
Fixing this type of bounce requires correctly configured SPF, DKIM, and DMARC records. Our free Domain Checker analyses all three in one scan and tells you exactly what to fix.
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