SMTP 354 Start Mail Input vs 500 Syntax Error
SMTP 354 (Start Mail Input) is a 3xx Positive Intermediate response, while 500 (Syntax Error) is a 5xx Permanent Negative response. 354 indicates that the server is ready to receive the message body. The client should begin sending the email content (headers and body) and terminate with a single line containing only a period (CRLF.CRLF). In contrast, 500 means that the server could not recognize the command due to a syntax error. The command line was malformed or the command is not recognized by this server.
Descripción
The server is ready to receive the message body. The client should begin sending the email content (headers and body) and terminate with a single line containing only a period (CRLF.CRLF).
Cuándo lo verás
After sending the DATA command. The server is now waiting for you to type or stream the email message, ending with a dot on its own line.
Cómo solucionarlo
Send your message content followed by a line with just a period (.) to signal the end. If you get an error after this, check that your message does not contain a bare period on a line by itself within the body.
Descripción
The server could not recognize the command due to a syntax error. The command line was malformed or the command is not recognized by this server.
Cuándo lo verás
When you send a command the server does not understand — often due to a typo, unsupported command, or an excessively long line.
Cómo solucionarlo
Check the command spelling and syntax against the SMTP specification. Ensure the command line does not exceed 512 characters and uses proper CRLF line endings.
Diferencias clave
354 is a 3xx Positive Intermediate response, while 500 is a 5xx Permanent Negative response.
SMTP 354: The server is ready to receive the message body. The client should begin sending the email content (headers and body) and terminate with a single line containing only a period (CRLF.CRLF).
SMTP 500: The server could not recognize the command due to a syntax error. The command line was malformed or the command is not recognized by this server.
You encounter 354 when after sending the DATA command. The server is now waiting for you to type or stream the email message, ending with a dot on its own line.
You encounter 500 when when you send a command the server does not understand — often due to a typo, unsupported command, or an excessively long line.
Cuándo usar cada uno
For 354 (Start Mail Input): Send your message content followed by a line with just a period (.) to signal the end. If you get an error after this, check that your message does not contain a bare period on a line by itself within the body. For 500 (Syntax Error): Check the command spelling and syntax against the SMTP specification. Ensure the command line does not exceed 512 characters and uses proper CRLF line endings.