[Exim] Two questions (related)

I have two questions, but first a bit of system background info. I am
on an intermittent dialup, using POP3 (fectmail) to collect mail. I
rewrite the outgoing From using a reqrite rule to lookup the user and
associate it with X@remotedomain. Thanks to the MAPS DUL I'm pretty
much forced to use a smarthost which requires me to do a POP3 check
to verify who I am before I actually send any email.

Now the questions.

Is there any way to make exim know that the remote email address
should be delivered here, and not sent on a round about route?
Occasionally something goes wrong with outgoing mail on my box but
the damn error mails need to go out before I reveive them (could get
into a vicious circle, that!). To complicate matters I might change
the From in the MUA, so ideally any solution should be able to deal
with that as well :-P

Secondly, is there a way for exim to force a fetchmail (or some other
POP3) connection before it tries to send mail?

Thanks

--
Gary
Statistics: the quantification of ignorance.