[JdeBP]

... but Sendmail was furiously trying to redeliver a massive mail queue of daily security run output messages? (-:

There is more than just your WWW browser and X applications running on a FreeBSD system.

[dijit]

Yes, of course, but maybe that's part of the problem.

FWIW, sendmail delivery to local mailboxes shouldn't need to retry, since it'll just dump in roots spool folder.