force smtp auth

[Doug McComber]

Hi, I've got smtp auth running with sendmail via the FreeBSD handbook.
 Now I'd like to set it up so that smtp auth is the only method
allowed for sending outgoing mail.

This is for a web server that runs Drupal.  I don't use the server for
email as I have that hosted elsewhere. I just want Drupal to be able
to send email (from localhost) via smtp auth. This is working right
now except mail can also be sent without using smtp auth.

Regards,
Doug