exim configuration: "Return-path" and "Sender" headers

[Arcady Genkin <a.genkin@utoronto.ca>]

I have both of these headers "wrong", i.e. they contain
antipode@main.wgaf.net, which is my user name at my local machine in
my home (unregistered, of course) domain.

As a result, some Majordomo's and some smtp servers discard my
messages (take them as spam?).

I'm using Slink+exim that came with it.

How can I rectify this problem? I know that "Sender" headers are not
to blame (read they are not supposed to cause any harm), but in our
imperfect world they do. And "Return-path" should be fixed too.

TIA!
-- 
Arcady Genkin
"... without money one gets nothing in this world, not even a certificate
of eternal blessedness in the other world..." (S. Kierkegaard)