[Exim] Using the -f flag

This is a multi-part message in MIME format.
--
[ Picked text/plain from multipart/alternative ]
I posted awhile back about some problems I've been having using the
-f[email] flag. From all indications, the problem is that the script
trying to use the flag isn't running as a trusted user. So how can I (or
my host) verify that the user the script is using actually is a trusted
user or not?

Thanks,

Matthew
--