Fair enough :). Are you saying that in general you don't give your email out, or are you saying you think the value prop for this particular app is too weak to give an email out for?
I don't want to give my email address out unless I actually want to be emailed by you (with something I care about, not with what you think I should be reading). On terrible sites that have not realized such basic facts but have software I really want (VMware for example), I use bugmenot or mailinator. Thereby this sort of thing only serves to reduce the amount of people that try your app and annoy those that want it bad enough into giving you a fake email. And a couple poor sods that get spammed by you later on, either because you decided to spam them, because you took improper care of your contact database or because your company got sold and stripped for assets (customer data = valuable).
They built an email list of hundreds of thousands of people who downloaded free software.
The list is a more valuable asset to them than anything else.