Revised MAILER() Declaration for m4 Configuration

The MAILER() declaration specifies support for delivery agents. To declare a delivery agent, use the following syntax.

MAILER(`symbolic_name')

In this new version of sendmail, the MAILER(`smtp') declaration now includes an additional mailer, dsmtp, which provides on-demand delivery by using the F=% mailer flag. The dsmtp mailer definition uses the new DSMTP_MAILER_ARGS, which defaults to IPC $h.