421 4.4.2: Bad Connection
The 421 4.4.2 soft bounce means the SMTP connection to the destination server failed or dropped mid-delivery. Learn what causes this and when to retry.
Published · Last verified · Maintained by TamingDNS
421
4.4.2
Bad Connection
Very Common
🔢 Enhanced Status Code Breakdown: 4.4.2
| Component | Value | Meaning |
|---|---|---|
| Class | 4 | Temporary failure (Soft bounce) |
| Subject | 4 | Network and routing |
| Detail | 2 | Bad Connection |
Per RFC 3463 Enhanced Mail System Status Codes. Class (X) = severity, Subject (Y) = category, Detail (Z) = specific condition.
💬 What This Error Means
The 'phone line' was cut mid-conversation. Your server started talking to the recipient's server, but the connection was suddenly dropped. This is a network-level glitch that your server will automatically try to fix by reconnecting.
Common Causes
- A brief internet hiccup between the two servers
- The two servers couldn't agree on a secure encryption method (TLS)
- The other server was overwhelmed and hung up to save resources
How to Fix This
- Your mail server will automatically try to reconnect and finish the delivery
- If this happens every time you send to this person, there might be a security setting mismatch between your servers
- If you're a large sender, check with your email provider to ensure your server settings are up to date
📚 Official Documentation
📋 Real-World Example Messages
These are real bounce message formats you might receive. Paste yours into the Bounce Decoder for instant analysis.
421 4.4.2 Bad connection 421 4.4.2 Connection dropped by remote host
🔗 Related Error Codes
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