I'll second this as a wish-list item -- I recently had to turn off
starttls for outbound messages as well, and was surprised that Courier
didn't gracefully fall-back.
Is there a flag, available today, that can be set that tells courier
to _try_ TLS? In other words, if STARTTLS is announced and you call
the bluff, rather than failing to deliver and deferring the message it
would retry without calling STARTTLS. If there isn't a flag that does
this, can it be added to a wish list? For karma sake, it would be
nice if it would log the failed STARTTLS attempt so that one could
contact the postmaster of that domain and notify him.