SMTP - protocol.how

SMTP Reference

Port 25

SMTP (Simple Mail Transfer Protocol) is used for sending emails between servers. It operates on port 25 and uses a command-response model.

HELO HELO <domain>

Identifies the client to the server

HELO mail.example.com

MAIL FROM MAIL FROM:<address>

Specifies the sender address

MAIL FROM:<sender@example.com>

RCPT TO RCPT TO:<address>

Specifies a recipient address

RCPT TO:<recipient@example.com>

DATA DATA

Starts message body input (end with single dot). Use Subject: <text> on its own line to set the email subject.

DATA

RSET RSET

Resets the mail transaction, clearing sender and recipients while keeping the connection open.

RSET

QUIT QUIT

Closes the connection

QUIT

HELP HELP [command]

Shows available commands or command help

HELPHELP MAIL