Mac to pc email problems

A friend who is on PC often forwards emails with pictures from her friend who is on a new Mac. (Her friend used to be on PC and we didn't have problems then.) Now, my friend says she gets the pics fine (embedded in the email) but by the time it gets to me, the pics are replaced by weird symbols and empty space. Some of the symbols are:
 or &g t; or  or om>

Is there some setting on the Mac or the PC that will fix this?