SMTP 211 System Status vs 220 Service Ready
Both SMTP 211 (System Status) and 220 (Service Ready) belong to the 2xx Positive Completion category. 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. Meanwhile, 220 means that the SMTP server is ready to begin the mail transaction. This greeting is the first response a client receives upon connecting, and it typically includes the server's hostname and software identificati
描述
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.
何时出现
When querying the mail server for its status or capabilities. The server is sharing diagnostic or informational details about itself.
如何修复
No fix needed — this is an informational response. If the status indicates a problem, review the server's configuration or contact the mail administrator.
描述
The SMTP server is ready to begin the mail transaction. This greeting is the first response a client receives upon connecting, and it typically includes the server's hostname and software identification.
何时出现
Immediately after establishing a TCP connection to the mail server on port 25, 465, or 587. This is the server's welcome banner confirming it is ready to accept commands.
如何修复
No fix needed — this confirms a successful connection. If you do not receive this greeting, check that the server is running, the port is correct, and no firewall is blocking the connection.
主要区别
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 220: The SMTP server is ready to begin the mail transaction. This greeting is the first response a client receives upon connecting, and it typically includes the server's hostname and software identificati
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 220 when immediately after establishing a TCP connection to the mail server on port 25, 465, or 587. This is the server's welcome banner confirming it is ready to accept commands.
何时使用哪个
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 220 (Service Ready): No fix needed — this confirms a successful connection. If you do not receive this greeting, check that the server is running, the port is correct, and no firewall is blocking the connection.