SMTP 235 Authentication Successful vs 451 Local Error
SMTP 235 (Authentication Successful) is a 2xx Positive Completion response, while 451 (Local Error) is a 4xx Transient Negative response. 235 indicates that the client has been successfully authenticated using the AUTH command. The server will now accept mail commands from this authenticated session. In contrast, 451 means that the requested action was aborted due to a local error in processing. The server encountered an internal issue that prevented it from completing the command.
描述
The client has been successfully authenticated using the AUTH command. The server will now accept mail commands from this authenticated session.
何时出现
After submitting valid credentials via the AUTH command (LOGIN, PLAIN, or other SASL mechanism). The server has verified your identity and you can now send mail.
如何修复
No fix needed — authentication succeeded. If you expected this but received a different code, double-check your username, password, and the authentication mechanism.
描述
The requested action was aborted due to a local error in processing. The server encountered an internal issue that prevented it from completing the command.
何时出现
When the receiving server hits an internal error such as a database failure, DNS lookup timeout, or anti-spam filter processing error.
如何修复
Retry the message later. If you control the server, check its logs for the specific error — common causes include DNS resolution failures, disk I/O errors, or database connectivity issues.
主要区别
235 is a 2xx Positive Completion response, while 451 is a 4xx Transient Negative response.
SMTP 235: The client has been successfully authenticated using the AUTH command. The server will now accept mail commands from this authenticated session.
SMTP 451: The requested action was aborted due to a local error in processing. The server encountered an internal issue that prevented it from completing the command.
You encounter 235 when after submitting valid credentials via the AUTH command (LOGIN, PLAIN, or other SASL mechanism). The server has verified your identity and you can now send mail.
You encounter 451 when when the receiving server hits an internal error such as a database failure, DNS lookup timeout, or anti-spam filter processing error.
何时使用哪个
For 235 (Authentication Successful): No fix needed — authentication succeeded. If you expected this but received a different code, double-check your username, password, and the authentication mechanism. For 451 (Local Error): Retry the message later. If you control the server, check its logs for the specific error — common causes include DNS resolution failures, disk I/O errors, or database connectivity issues.