550 5.7.26: DMARC Policy Violation
The 550 5.7.26 bounce means your email failed DMARC and was rejected. Learn why DMARC violations happen and how to fix SPF and DKIM alignment.
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550
5.7.26
DMARC Policy Violation
Very Common
🔢 Enhanced Status Code Breakdown: 5.7.26
| Component | Value | Meaning |
|---|---|---|
| Class | 5 | Permanent failure (Hard bounce) |
| Subject | 7 | Security or policy |
| Detail | 26 | DMARC Policy Violation |
Per RFC 3463 Enhanced Mail System Status Codes. Class (X) = severity, Subject (Y) = category, Detail (Z) = specific condition.
💬 What This Error Means
Your email failed its 'ID check' (DMARC). The receiving server tried to verify that the email actually came from you, but the authentication didn't match up with your domain. Because their security policy is set to 'reject,' they didn't let the message through.
Common Causes
- Neither SPF nor DKIM could verify that the email came from your domain
- Your email service is "authorized" but it's sending under its own domain instead of yours (alignment failure)
- You're using a third-party service (like a CRM or helpdesk) that hasn't been fully set up with your DKIM keys
How to Fix This
- Ensure your email service is set up to sign messages with your own domain's DKIM keys
- Check that your SPF record includes all the services you use to send mail
- Use our Domain Checker to see exactly where the "alignment" is failing
- Look at your DMARC reports to see if any legitimate mail is being blocked
📚 Official Documentation
Google enforces DMARC p=reject strictly. Gmail bulk-sender rules (Feb 2024) require DMARC at minimum p=none for senders of 5,000+ messages a day.
📖 Google Workspace / Gmail documentation → Browse all Google Workspace / Gmail error codes →Microsoft 365 enforces DMARC rejection for inbound mail to Office 365 mailboxes. From May 2025, Outlook.com/Hotmail/Live also require SPF, DKIM and DMARC for senders over 5,000 messages a day, and reject non-compliant mail with 550 5.7.515.
📖 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.
From: [email protected] Subject: Undeliverable Status: 5.7.26 Diagnostic-Code: smtp; 550 5.7.26 This message does not pass authentication checks (SPF and DKIM both do not pass).
🔗 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.
Run a Free Domain Authentication Check →Got a bounce message to decode?
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