SMTP 220 Service Ready vs 501 Syntax Error in Parameters
SMTP 220 (Service Ready) is a 2xx Positive Completion response, while 501 (Syntax Error in Parameters) is a 5xx Permanent Negative response. 220 indicates 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 In contrast, 501 means that the command was recognized but the parameters or arguments are syntactically invalid. The server understood what you wanted to do but could not parse the details.
Deskripsi
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.
Ketika Anda Melihatnya
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.
Cara Memperbaiki
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.
Deskripsi
The command was recognized but the parameters or arguments are syntactically invalid. The server understood what you wanted to do but could not parse the details.
Ketika Anda Melihatnya
When a command like MAIL FROM or RCPT TO has a malformed email address, missing angle brackets, or invalid characters in the arguments.
Cara Memperbaiki
Review the parameter format — email addresses should be enclosed in angle brackets (e.g., <[email protected]>). Check for stray spaces, missing colons, or encoding issues.
Perbedaan Utama
220 is a 2xx Positive Completion response, while 501 is a 5xx Permanent Negative response.
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
SMTP 501: The command was recognized but the parameters or arguments are syntactically invalid. The server understood what you wanted to do but could not parse the details.
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.
You encounter 501 when when a command like MAIL FROM or RCPT TO has a malformed email address, missing angle brackets, or invalid characters in the arguments.
Kapan Menggunakan Yang Mana
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. For 501 (Syntax Error in Parameters): Review the parameter format — email addresses should be enclosed in angle brackets (e.g., <[email protected]>). Check for stray spaces, missing colons, or encoding issues.