SMTP 354 Start Mail Input vs 530 Authentication Required
SMTP 354 (Start Mail Input) is a 3xx Positive Intermediate response, while 530 (Authentication Required) 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, 530 means that the server requires authentication before accepting mail commands. You must issue the AUTH command with valid credentials before attempting to send mail.
Description
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).
When You See It
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.
How to Fix
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.
Description
The server requires authentication before accepting mail commands. You must issue the AUTH command with valid credentials before attempting to send mail.
When You See It
When trying to send mail through a server that requires authentication (typical for submission on port 587) without first logging in with the AUTH command.
How to Fix
Authenticate using the AUTH command with your username and password before sending MAIL FROM. Ensure your email client is configured with the correct SMTP credentials and authentication method.
Key Differences
354 is a 3xx Positive Intermediate response, while 530 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 530: The server requires authentication before accepting mail commands. You must issue the AUTH command with valid credentials before attempting to send mail.
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 530 when when trying to send mail through a server that requires authentication (typical for submission on port 587) without first logging in with the AUTH command.
When to Use Which
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 530 (Authentication Required): Authenticate using the AUTH command with your username and password before sending MAIL FROM. Ensure your email client is configured with the correct SMTP credentials and authentication method.