Why are you working so hard at making fetchmail invoke exim as an MDA?
Running exim as a daemon (bound only to localhost if necessary) and
getting fetchmail to do SMTP submission into exim works very well for
me:-
# Configuration created Tue Mar 9 15:22:58 1999 by fetchmailconf
set postmaster "nigel@???"
poll isp.mail.server with proto POP3
user "username" there with password "guesswhat" is
nigel+pobox@??? here
[I use + as a suffix separator in case that causes confusion]
Nigel.
--
[ Nigel Metheringham Nigel.Metheringham@??? ]
[ Phone: +44 1423 850000 Fax +44 1423 858866 ]