displaying jpg and gif differs to other images in mail

[Oliver Rohloff]

i tried to read a mail with different image-attechements.
there where types of bmp, pcx, gif and jpg. All of them are
opened with photoshop by default in windows. why are jpg and gif
opened in a new browserwindow instead of opened with photoshop
like bmp and pcx? is it possible to change the behavior of opening
in a browserwindows?
thx oli