--On Tuesday, August 10, 2010 09:48 -0700 Dave CROCKER
<dhc(_at_)dcrocker(_dot_)net> wrote:
As I recall, delivermail didn't do queuing. So, yes, the
delivery attempt was immediate.
Sendmail behaved the same way, for a first attempt, and did
queuing only if that attempt failed.
MMDF always did queuing first, spawning a delivery attempt
afterward. (Submission and delivery were independent Unix
processes.)
And IIR, several of the small computer-based things, including
PC/TCP, would make a direct attempt to deliver and send mail to
what we would now call a submission server only if that single
direct delivery attempt failed.
john