Qmail, setting as default mailer

Configure mailwrapper. Edit the file /etc/mail/mailer.conf to look like this:

# /etc/mail/mailer.conf
# freebsd mailwrapper configuration, for qmail
# ===
sendmail    /var/qmail/bin/sendmail
send-mail   /var/qmail/bin/sendmail
mailq       /var/qmail/bin/qmail-qread
newaliases  /var/qmail/bin/newaliases

### that's all, folks!

This maps the appropriate qmail executables to their sendmail aliases. That's it for FreeBSD.