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Bounce Decoder: 550 5.1.0

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

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550 5.1.0 — Other Address Status

The 550 5.1.0 SMTP error is a generic addressing rejection. Learn what causes this bounce and how to resolve it.

🔴
Permanent Failure (Hard Bounce)
SMTP Code
550
Enhanced Code
5.1.0
Category
Other Address Status
Frequency
Common

🔢 Enhanced Status Code Breakdown: 5.1.0

Component Value Meaning
Class 5 Permanent failure
Subject 1 Addressing
Detail 0 Other Address Status

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

💬 What This Error Means

The recipient address was rejected for an unspecified reason. This is a generic addressing error — the domain may exist but the specific mailbox cannot receive mail.

Common Causes

  • The specific mailbox is not valid on this server
  • Server-level address filtering or blocklist
  • Catch-all delivery is disabled for this domain

How to Fix This

  • Verify the email address is correct and currently active
  • Try contacting the recipient through an alternative channel
  • Check if the domain has changed its email provider

📋 Real-World Example Messages

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

550 5.1.0 Address rejected
550 5.1.0 <[email protected]>: Sender address rejected: Domain not found

🔗 Related Error Codes

550 5.1.1
Mailbox Does Not Exist
550 5.1.2
Bad Destination Domain

📚 Official Documentation

↗ RFC 3463 — Enhanced Mail System Status Codes
🔍

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