550 5.7.23: SPF Validation Failed

🔢 Enhanced Status Code Breakdown: 5.7.23

Per RFC 3463 Enhanced Mail System Status Codes. Class (X) = severity, Subject (Y) = category, Detail (Z) = specific condition.

💬 What This Error Means

Your domain's 'authorized sender list' (SPF) doesn't include the server you're currently using. When the receiving server checked your domain's records, it didn't see the sending IP address on the approved list, so it rejected the email to protect against spoofing.

Common Causes

• You're sending from a new service or IP that isn't in your SPF record yet
• Your SPF record has a small typo or syntax error
• Your SPF record is too complex and exceeds the "10 lookup" limit
• You have multiple SPF records, which isn't allowed

How to Fix This

• Use our SPF Checker to see exactly what's wrong with your record
• Add the IP address or service (like SendGrid or Mailchimp) to your SPF record
• If your record is too long, look into "SPF flattening" or simplify your includes
• Make sure you only have one SPF record starting with "v=spf1"

📚 Official Documentation

📋 Real-World Example Messages

These are real bounce message formats you might receive. Paste yours into the Bounce Decoder for instant analysis.

550 5.7.23 The message was rejected because of SPF validation failure

🔗 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.