attachment problem

[fafi]

hi
i want to send an outlook messege with a banner(animated gif or JPG).
when i am sending it to others, sometimes they get the message with
attachment icon and sometimes without it(of course the bunner is still
there).
i tried to find the case where no attach icon is not displayed without
seccsess. i checked where all the clients are OUTLOOK 2000 or 2003, i
tried using RTF or HTML, in or out from the sender domain but i cant
find consistent behaviur. i want it to send without display the icon at
recivers inbox.
can someone help?