Following up to myself...:

> I'll admit that it's a long time since I configured sendmail last,
> and I could not find an easy configuration change to make it listen
> only to 127.0.0.1, so now some of my systems have an exposed
> listener on port 25 where I did not have one before and where I
> didn't really want one.  Tweaking the .mc file for the sendmail
> configuration to make it listen only to 127.0.0.1 does not qualify
> as "an easy configuratin change".

It has been politely pointed out to me that the sendmail section in
/etc/defaults/rc.conf contains an option string for sendmail to have
it listen only on 127.0.0.1 and/or ::1.  I've seen that section, but
apparently did not "read" it.  Oh, well.

That doesn't change the main argument -- it's still necessary to
"configure stuff" for the system to be able to send e-mail.

Regards,

- Håvard