SMTP 211 System Status vs 551 User Not Local
SMTP 211 (System Status) is a 2xx Positive Completion response, while 551 (User Not Local) is a 5xx Permanent 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, 551 means that the recipient is not local to this server and the server does not accept mail for forwarding. Unlike 251, this is a rejection — the server will not relay the message.
Descripción
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.
Cuándo lo verás
When querying the mail server for its status or capabilities. The server is sharing diagnostic or informational details about itself.
Cómo solucionarlo
No fix needed — this is an informational response. If the status indicates a problem, review the server's configuration or contact the mail administrator.
Descripción
The recipient is not local to this server and the server does not accept mail for forwarding. Unlike 251, this is a rejection — the server will not relay the message.
Cuándo lo verás
When sending to a recipient that has moved or whose mailbox is hosted elsewhere, and this server refuses to forward the message to the new location.
Cómo solucionarlo
Check the server's response for a forwarding address and resend directly to that address. Update your contact records if the recipient has permanently moved to a new mail server.
Diferencias clave
211 is a 2xx Positive Completion response, while 551 is a 5xx Permanent 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 551: The recipient is not local to this server and the server does not accept mail for forwarding. Unlike 251, this is a rejection — the server will not relay the message.
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 551 when when sending to a recipient that has moved or whose mailbox is hosted elsewhere, and this server refuses to forward the message to the new location.
Cuándo usar cada uno
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 551 (User Not Local): Check the server's response for a forwarding address and resend directly to that address. Update your contact records if the recipient has permanently moved to a new mail server.