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Bounce Decoder: 550 5.4.4

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550 5.4.4 — No Route to Destination

The 550 5.4.4 bounce means the sending server cannot find any mail servers for the recipient domain. Learn how to diagnose and fix this routing error.

🔴
Permanent Failure (Hard Bounce)
SMTP Code
550
Enhanced Code
5.4.4
Category
No Route to Destination
Frequency
Very Common

🔢 Enhanced Status Code Breakdown: 5.4.4

Component Value Meaning
Class 5 Permanent failure
Subject 4 Network and routing
Detail 4 No Route to Destination

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

💬 What This Error Means

The sending server could not find any mail servers to deliver to for this domain. The domain likely has no MX records or cannot be resolved in DNS.

Common Causes

  • No MX records configured for the recipient domain
  • DNS resolution failure for the domain
  • The domain has expired or been deleted

How to Fix This

  • Verify the domain part of the address is correct
  • Use our Domain Checker to see if the domain has working MX records
  • If it is your domain, check your DNS configuration immediately

📋 Real-World Example Messages

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

550 5.4.4 Unable to route: recipient domain has no MX record
550 5.4.4 ROUTING.NoMX; MX record for domain doesn't exist

🔗 Related Error Codes

550 5.1.2
Bad Destination Domain
550 5.4.1
Recipient Address Rejected

📚 Official Documentation

↗ RFC 5321 — MX record lookup
🔍

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