[Exim] Using exim with IMP

Hello!

I am using exim together with the Webmail interface IMP. The mails are
send under the userid the web server is using. So if the delivery of a
mail fails the mail returns to the user "wwwrun" (or whatever the user
of the web server is...). I tried some rewriting rules but without any
success so far. Using a rule which only changes the "Sender" does not
work. How can I rewrite the rest of the header so that the return-path
points to the user who sent the mail (or better make even exim believe
that it came from this user...).

Any ideas?

Thank you.

Greetings, Jan Suchanek

--
Jan Suchanek,
Universitaet Ulm, URG, Fakultaet fuer Informatik,
89069 Ulm, Germany
Raum: O27/243

Tel.: +49/(0)731-5024205, Fax: +49/(0)731-5024202