The ${daemon_name} macro contains the value of the DaemonPortOptions=Name option (See this section) whenever an inbound connection is accepted. The names assigned in the default configuration file are MTA (for the daemon that listens on port 25), and MSA (for the MSP daemon that listens on port 587).

As distributed, this ${daemon_name} macro is not used in the configuration file. It is, however, available to you for use in designing your own particular rule sets. Note that a $& prefix is necessary when you reference this macro in rules (that is, use $&{daemon_name}, not ${daemon_name}).

${daemon_name} is transient. If it is defined in the configuration file or in the command line, that definition can be ignored by sendmail.