Scanning and auto-deleting your email, combined with the Gatekeeper technology wich houses the possibility of Apple telling me what Apps I can or can not run makes me seriously start to wonder the direction Apple is headed... Edit: Gatekeeper is OSX technology. It allows users to only install Apple certified Apps on your mac , not your phone. It's fairly new and possible to turn it off (for now at least).
It's easy to temporarily disable Gatekeeper, install what you want, and then turn it back on. In no way does it prevent you from running what you want on your own computer. The point is to put another wall against unintended installs (aka exploits), and corrupted/infected versions of known-good software.
Please don't. Just right click and choose open. You will be able to open it, and whitelist the app in the process.