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Bounce Decoder: 550 5.7.25

SPF, DKIM, DMARC, FCrDNS, Blacklists & Inbox Prediction

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550 5.7.25 — Reverse DNS (PTR) Validation Failed

The 550 5.7.25 bounce means your sending IP has no valid PTR record or fails forward-confirmed reverse DNS. Learn how to fix this deliverability problem.

🔴
Permanent Failure (Hard Bounce)
SMTP Code
550
Enhanced Code
5.7.25
Category
Reverse DNS (PTR) Validation Failed
Frequency
Common

🔢 Enhanced Status Code Breakdown: 5.7.25

Component Value Meaning
Class 5 Permanent failure
Subject 7 Security or policy
Detail 25 Reverse DNS (PTR) Validation Failed

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

💬 What This Error Means

The receiving server requires a valid reverse DNS (PTR) record for your sending IP. Your IP either has no PTR record, or the forward and reverse DNS don't match (FCrDNS failure).

Common Causes

  • No PTR record configured for your sending IP
  • PTR record doesn't match your sending domain
  • Shared hosting IP with a generic PTR record

How to Fix This

  • Contact your hosting provider or ISP to set a PTR record for your sending IP
  • The PTR should point to your mail server hostname (e.g. mail.yourdomain.com)
  • Ensure the hostname also resolves back to the sending IP (forward-confirmed)

📋 Real-World Example Messages

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

550 5.7.25 Reverse DNS validation failed for IP
550 5.7.25 [x.x.x.x] does not have a proper PTR record

🔗 Related Error Codes

550 5.7.1
Message Rejected by Policy

📚 Official Documentation

↗ RFC 3463 — Enhanced Status Codes
🔍

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