I need a test done, if you have Mozilla as the default mail client. Try the following:

DECLARE INTEGER ShellExecute IN shell32.dll ;
  INTEGER hndWin, STRING cAction, STRING cFileName, ;
  STRING cParams, STRING cDir, INTEGER nShowWin

cFileName = "mailto:john@mycompany.com?subject=How To Send Mail"
cAction = "open"
ShellExecute(0,cAction,cFileName,"","",1)

Does the above open the mail client and properly populate the To: field?

Also, using IE, will clicking on a mailto: link bring up the client properly? I'm trying to determine if I have a blown install or registry problem, or I'm dealing with a Mozilla bug. TIA.