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.
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550
5.1.0
Other Address Status
Common
🔢 Enhanced Status Code Breakdown: 5.1.0
| Component | Value | Meaning |
|---|---|---|
| Class | 5 | Permanent failure (Hard bounce) |
| Subject | 1 | Address / Destination |
| 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's server rejected the address, but didn't give a specific reason why. It's a general 'No' from the other side, often because of internal rules they have set up for who can receive mail.
Common Causes
- The address exists, but it's currently not allowed to receive external mail
- A specific security filter on the recipient's side has blocked your domain
- The server is configured to only accept mail for certain "active" employees
How to Fix This
- Double-check that you have the right email address
- Try reaching out to them through another channel to see if their email has changed
- If this is a business address, check if the company has recently changed their name or domain
📚 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 5.1.0 Address rejected 550 5.1.0 <[email protected]>: Sender address rejected: Domain not found
🔗 Related Error Codes
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