SMTP authentication for sendmail using binary-only host system

In looking at
https://docs.freebsd.org/en/books/handbook/mail/#sendmail
there's a concise description of setting up smtp authentication
for sendmail but it seems to assume a self-hosted installation,
with a working /usr/src.

Is there a corresponding description that's usable for the case
of a binary-only installation based on freebsd-update and pkg?

Thanks for reading,

bob prohaska