[Exim] Rewriting

I have a webserver with lots of scripts and form2mail things
and whatever things I happily do not have to care about. Our
webmaster (and I, pushing that issue, methinks) have all
customers at least supply a valid From: line, though the
envelope is still ww-data (the user apache runs under) in
most cases (-f is "too complicated, what does it mean").

Now, a rewrite of the envelope with what is in the From:
field works how? A conditional rewrite, but the first
part of the rewrite is static.

www-data@??? xxx@??? Fr

Now, any pointers to how this can be achieved?

Thanks,
Alexander

--
Alexander Koch - <>< - WWJD - aka Efraim - PGP 0xE7694969 - ARGH-RIPE