Postfix can be set up to replace smtpd entirely. Please read the
documentation at file://${PREFIX}/share/doc/postfix/html/index.html or
${HOMEPAGE} carefully before you decide to do this!

To replace smtpd with Postfix you have to install a new mailer.conf
using the following command:

    ${PREFIX}/sbin/postfix-enable

If you want to restore smtpd, this is done using the following command:

    ${PREFIX}/sbin/postfix-disable