I have adopted the excellent method described here to associate a file type with my app. My issue is that when the file is attached to an email and the user touches the attachment, instead of the app immediately loading, the user gets a "quicklook" of the contents of the file, and has to click on the button in the top right hand corner in order to "Open With" my app.
I want to DISABLE quicklook in respect of my custom extension (e.g. "*.CUS"), and I want the email app to simply go directly to my app when the attachment is 'clicked'.