jpeg – Windows98 verses Windows Me

Windows 98B can send (email) a photo/picture in jpeg format to someone with WindowsMe and they can open it but, if someone who is sending a jpeg with WindowsMe to someone with Windows 98B in comes over the email as “Winmail.dat Does anyone know a why to fix this. I 4 people with Window 98 and 1 with Windows ME and the furstration level is rising. We have used different mailservers etc but nothing seems to work. Thanks.