Steven W. Orr :

You seem to be using Majordomo, perhaps that is the cause of the
problem.

I don't know Majordomo but I've seen that it can use some
"enhancements" like bulk_mailer and TLB that will run multiple sendmail
queues.

So it probably wasn't sendmail by itself opening multiple connections,
which was the strange part, it could be either Majordomo itself running
sendmail several times or one of those add-ons. I don't know how to
correct that problem.
--
René Berber