## MailFront

# Protocol: smtp

The SMTP protocol module has the following features:

- Handles RFC 2554 SMTP authentication. Note that the require-auth plugin and/or the relayclient plugin will need to be loaded to make use of this authentication.
- Automatically handles either bare NL or RFC 821 / RFC 2821 compliant CR/NL end-of-line conventions.
- Times out connections after `$TIMEOUT` seconds of inactivity (defaults to 1200 seconds or 20 minutes), or `$SESSION_TIMEOUT` seconds after the connection was established (defaults to 86400 seconds or 24 hours).
- All error responses are logged.
- Handles (ignores) RFC 1869 extended parameters on the `RCPT TO:` and `MAIL FROM:` commands.
- Initial greeting message is configureable by `$SMTPGREETING`. If that is not set, the greeting is generated based on the domain name in `${$PROTO}LOCALHOST` set by the invoking UCSPI server such as tcpserver.
- Supports RFC 1870 SMTP Service Extension for Message Size Declaration.
- If `$MAXNOTIMPL` is set, clients are disconnected if they send more than the specified number of commands that result in a "`500 Not implemented.`" error.