SMTP 250 OK vs 455 Server Unable to Accommodate
SMTP 250 (OK) is a 2xx Positive Completion response, while 455 (Server Unable to Accommodate) is a 4xx Transient Negative response. 250 indicates that the requested mail action has been completed successfully. This is the most common positive response in SMTP, returned after HELO/EHLO, MAIL FROM, RCPT TO, and DATA completion. In contrast, 455 means that the server is currently unable to accommodate the requested parameters. This is a general temporary failure indicating the server cannot process the specific request at this time.
설명
The requested mail action has been completed successfully. This is the most common positive response in SMTP, returned after HELO/EHLO, MAIL FROM, RCPT TO, and DATA completion.
이 코드를 보게 되는 경우
After nearly every successful SMTP command — greeting, specifying sender, adding recipients, or completing message delivery. This is the standard success confirmation.
해결 방법
No fix needed — the command was accepted. If a command that should succeed returns a different code, check the command syntax and server policies.
설명
The server is currently unable to accommodate the requested parameters. This is a general temporary failure indicating the server cannot process the specific request at this time.
이 코드를 보게 되는 경우
When the server temporarily cannot handle a specific aspect of your request, such as a particular extension or parameter that requires resources not currently available.
해결 방법
Retry the command later or try with different parameters. If the error persists, simplify the request or contact the server administrator to check resource availability.
주요 차이점
250 is a 2xx Positive Completion response, while 455 is a 4xx Transient Negative response.
SMTP 250: The requested mail action has been completed successfully. This is the most common positive response in SMTP, returned after HELO/EHLO, MAIL FROM, RCPT TO, and DATA completion.
SMTP 455: The server is currently unable to accommodate the requested parameters. This is a general temporary failure indicating the server cannot process the specific request at this time.
You encounter 250 when after nearly every successful SMTP command — greeting, specifying sender, adding recipients, or completing message delivery. This is the standard success confirmation.
You encounter 455 when when the server temporarily cannot handle a specific aspect of your request, such as a particular extension or parameter that requires resources not currently available.
언제 어떤 것을 사용할지
For 250 (OK): No fix needed — the command was accepted. If a command that should succeed returns a different code, check the command syntax and server policies. For 455 (Server Unable to Accommodate): Retry the command later or try with different parameters. If the error persists, simplify the request or contact the server administrator to check resource availability.