> I would venture most larger Exim installations have local MUA
> recipient verification failures generate bounces,
That's an interesting question. Though I know what my preference is, I
have no idea what most other sites do. I'd be curious to hear from
anyone who wants to speak up.
Do you verify recipients during an MUA submission SMTP conversation, or
do you let them all through and let the natural bounce mechanism notify
the users?
(Interestingly, several years ago I went to work for a large commercial
email vendor. As a traditional Unix guy, it seemed obvious to me that
it should be the opposite of what my preference is these days. Maybe I
made fewer typos in those days. :-)