SMTP 214 Help Message vs 450 Mailbox Unavailable
SMTP 214 (Help Message) is a 2xx Positive Completion response, while 450 (Mailbox Unavailable) is a 4xx Transient 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, 450 means that the requested mail action was not taken because the mailbox is temporarily unavailable. This could be due to the mailbox being locked by another process or a temporary policy restriction.
Description
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.
Quand vous le voyez
After sending the HELP command to the SMTP server. The response lists available commands or provides usage details for the command you specified.
Comment résoudre
No fix needed — this is a normal informational response. Use the provided help text to understand which commands the server supports.
Description
The requested mail action was not taken because the mailbox is temporarily unavailable. This could be due to the mailbox being locked by another process or a temporary policy restriction.
Quand vous le voyez
When the recipient's mailbox exists but is currently locked, busy, or subject to greylisting. The server is asking you to try again later.
Comment résoudre
Retry delivery after a few minutes. If using greylisting, the second attempt will typically succeed. For persistent failures, check if the recipient's mailbox is full or disabled.
Différences clés
214 is a 2xx Positive Completion response, while 450 is a 4xx Transient 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 450: The requested mail action was not taken because the mailbox is temporarily unavailable. This could be due to the mailbox being locked by another process or a temporary policy restriction.
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 450 when when the recipient's mailbox exists but is currently locked, busy, or subject to greylisting. The server is asking you to try again later.
Quand utiliser lequel
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 450 (Mailbox Unavailable): Retry delivery after a few minutes. If using greylisting, the second attempt will typically succeed. For persistent failures, check if the recipient's mailbox is full or disabled.