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.
4.4.2
| Component | Value | Meaning |
|---|---|---|
| Class | 4 | Persistent transient failure (temporary) |
| 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.
The SMTP connection to the recipient's mail server was established but then failed or dropped before the message could be delivered. This is a network-level problem that your mail server will retry.
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
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