''F=R'' '''


Use a reserved TCP port V8.6 and above

The F=R delivery agent flag causes sendmail to connect on a reserved (privileged) TCP port for additional security. Privileged Internet ports are those in the range of 0 to 1023. Only root is allowed to bind to such ports. The sendmail program calls rresvport(3) to obtain a socket on its selected port. Note that this is done only when instantiating an outgoing connection.

This delivery agent flag is suitable only for use with the A=TCP delivery agents. Note that sendmail is usually started by root when run as a daemon.

    Part I: Build and Install
    Part II: Administration
    Part III: The Configuration File
    Chapter 21. The D (Define a Macro) Configuration Command
    Chapter 24. The O (Options) Configuration Command