[Exim] Getting rejects for sending Spam - Sender set wrong

I am writing this from webmail at work; so the header will not show what I'm
talking about here.

When I send a message, Sender: says ajlewis2@sidekick. I want it to be
ajlewis2@???. I think I might have changed qualify_domain to sidekick
when I first installed Debian, because root mail was going to my ISP. I
currently have this in exim.conf

qualify_domain sidekick
local_domains localhost:sidekick

Is there some way I can get the Sender to be my actual email address and not
be sending local mail to my ISP. They got quite upset getting mail to root
there. I saw some posts saying to make the qualify_domain intac.com, but I'm
reluctant to do that if I am going to be having the messages to root going off
to my ISP.

Thanks.
--
Anita
GnuPG key: 1024D/9EDAC910