By default, FreeBSD uses the file /etc/mail/freebsd.mc to configure SendMail. While you're certainly free to modify this file for your own local needs, it's better to use your own separate file. Here is how you can do so:

1. Decide upon a name for your SendMail configuration file. Experience suggests choosing something like host.domain.com.mc
2. Add the line:

   SENDMAIL_MC=/etc/mail/host.domain.com.mc

   to /etc/make.conf.
3. Create the file you just specified:

   cd /etc/mail; cp -p freebsd.mc host.domain.com.mc

4. In the future, make all of your local changes to this file. FreeBSD will use your new file to generate the sendmail.cf file.

-- KirkStrauser - 20 Aug 2002