SMTP 214 Help Message vs 553 Mailbox Name Invalid
SMTP 214 (Help Message) is a 2xx Positive Completion response, while 553 (Mailbox Name Invalid) is a 5xx Permanent Negative response. 214 indicates that a help message response containing information about the server's supported commands or a specific command's usage. This is a human-readable reply to the HELP command. In contrast, 553 means that the requested action was not taken because the mailbox name is syntactically incorrect. The email address does not conform to the expected format.
説明
A help message response containing information about the server's supported commands or a specific command's usage. This is a human-readable reply to the HELP command.
このコードが表示される場合
After sending the HELP command to the SMTP server. The response lists available commands or provides usage details for the command you specified.
解決方法
No fix needed — this is a normal informational response. Use the provided help text to understand which commands the server supports.
説明
The requested action was not taken because the mailbox name is syntactically incorrect. The email address does not conform to the expected format.
このコードが表示される場合
When the sender or recipient address contains invalid characters, improper formatting, or violates the server's naming conventions.
解決方法
Check the email address format — ensure it follows the standard [email protected] pattern with valid characters. Remove any spaces, special characters, or encoding issues from the address.
主な違い
214 is a 2xx Positive Completion response, while 553 is a 5xx Permanent Negative response.
SMTP 214: A help message response containing information about the server's supported commands or a specific command's usage. This is a human-readable reply to the HELP command.
SMTP 553: The requested action was not taken because the mailbox name is syntactically incorrect. The email address does not conform to the expected format.
You encounter 214 when after sending the HELP command to the SMTP server. The response lists available commands or provides usage details for the command you specified.
You encounter 553 when when the sender or recipient address contains invalid characters, improper formatting, or violates the server's naming conventions.
どちらをいつ使うか
For 214 (Help Message): No fix needed — this is a normal informational response. Use the provided help text to understand which commands the server supports. For 553 (Mailbox Name Invalid): Check the email address format — ensure it follows the standard [email protected] pattern with valid characters. Remove any spaces, special characters, or encoding issues from the address.