If you email or post them anything, you’ll get a rejection immediately for legal reasons. A policy on idea submission is actually on their website (although I can’t find it right now) and it ain’t pretty. The company needs to protect itself from being accused of IP theft; if you send them something and they didn’t go through the proper motions of transferring the IP, you could later try suing them. It’s all pretty dumb, but that’s how it is. Simple feedback and bug reports through the feedback channels are all they’re willing to accept. If you really want to show them something and would like a job, push for a meeting.