Ok perhaps this will do the trick:
In a user's .forward file::
#Exim Filter <- do not remove this line!
pipe "/path/to/prog email@???"
seen finish
In this case exim will pass the email for the user to /path/to/prog's STDIN with email@??? as it's argument.
Then simply stop processing the email.
So it would be up to /path/to/prog to either deliver the mail or quietly drop it to oblivionright?
So in /path/to/prog I'd have to:
a) if I don't want to send the message just stop the script
b) if I want to send the original or modified message open a pipe in my script to exim to send it.
Is this assumption correct?
Now the last question would be:
What program and options would I pipe the original/modified message to to
have it delivered directly to the user instead of reprocessing
it and getting a mail loop?
TIA
Dan