How to get in-message display of gifs

I attach a gif file to a mail message sent from the netscape mua direct to 
mhonarch:

mymailalias: /local/mhonarc/wrapper mhonarc -add -quiet -rcfile myresfile

mhonarch detects the gif and generates the neccessary html to display the gif 
in 
the body of the archived message. 

This does not happen if I use eudora, or Pegasus or MS outlook. anyone know 
where 
I should look to fix this, please?