Most of the time, if I directly link to an unknown file type, the browser asks the user to download or open the file.

If it's a common MS file, it might just open in the browser.

I created a file with an extension of SMP and linked to it.

It threw a 400 error.

If I add a content/header to it and specified the application/octet-stream filetype, it worked. but I don't want to write that code for everyone of these.

Am I missing something?