Email headers

Right now RT2 reworks email ‘From:’ header when it emails a copy to
AdminCc or Cc. I’d like to have the sender/requestor email address shows
in the ‘From:’ header in the emails AdminCc and Cc receive. Where in
the codes could I change this? Could this be in the customized templates?
If so, what variable should I put in to pull out the sender/requestor’s
email address?

Thanks for the help,
Sherrill (Pei-chih) Verbrugge