When the person who has the rights sends e-mail, they need to enable the FROM field (usually under View->From: in the actual e-mail). They would simply populate the FROM field with your userID/mail account. Exchange should then allow the e-mail to go through, and the recipient will see in the from area "From [sender] on behalf of [user]"
Ken
"cckens is a nick... why the H-E- double-hockey-sticks am I using a nick for a name? Am I afraid of who I am?"
-me
"...don't know why, but I think of chickens when I see that nick...maybe even choking chickens???"
-Tony (wahnula)