SMTP 211 System Status vs 450 Mailbox Unavailable
SMTP 211 (System Status) is a 2xx Positive Completion response, while 450 (Mailbox Unavailable) is a 4xx Transient Negative response. 211 indicates that a system status reply providing information about the mail server's current state. This is typically sent in response to a HELP or system inquiry 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.
설명
A system status reply providing information about the mail server's current state. This is typically sent in response to a HELP or system inquiry command.
이 코드를 보게 되는 경우
When querying the mail server for its status or capabilities. The server is sharing diagnostic or informational details about itself.
해결 방법
No fix needed — this is an informational response. If the status indicates a problem, review the server's configuration or contact the mail administrator.
설명
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.
이 코드를 보게 되는 경우
When the recipient's mailbox exists but is currently locked, busy, or subject to greylisting. The server is asking you to try again later.
해결 방법
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.
주요 차이점
211 is a 2xx Positive Completion response, while 450 is a 4xx Transient Negative response.
SMTP 211: A system status reply providing information about the mail server's current state. This is typically sent in response to a HELP or system inquiry 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 211 when when querying the mail server for its status or capabilities. The server is sharing diagnostic or informational details about itself.
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.
언제 어떤 것을 사용할지
For 211 (System Status): No fix needed — this is an informational response. If the status indicates a problem, review the server's configuration or contact the mail administrator. 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.