Just pre-purchased my physical Summerset Collector's Edition at Amazon. How do I demonstrate to Zenimax that I have done this? I seem to remember sending my Amazon invoice in before, on an earlier pre-purchase (was that for Morrowind? or a completely different game? I can't remember).
This doesn't need to happen "immediately", I don't mind waiting until May 21, but at some point pre-purchasers of physical editions will need to demonstrate it was a PRE-purchase. Having Amazon issue some sort of in-game code at time of purchase, via email, would be an effective way to streamline this sort of thing.