> Are you sure that the mail haven't been queued?
> You know that there are two different mail queues nowadays?

great surprise for me!

> To check the outgoing mail, you should run "mailq -Ac"
> (Don't know offhand what the equivalent sendmail command is.)

OK, mailq -Ac reports more than ten different messages in the
submission queue, including year-olds..  I see my test message
in this queue.
However I do not understand why message did not fall into
the usual MTA queue?   I start sendmail in "deferred lookup" mode
So I expect that in case there is no internet connection
and it cannot resolve names, the message will wait in the queue.
And actually it worked this way some time ago.