I often just briefly want to see what the fuzz is all about. The app then "tricks me" into providing them with an email address, by pretending they need this as an identifier, most of the time in order to create an account. They then feel free to send me "Greg from blahblah app"-Emails.
To me, this is spam. It is an email I do not want. To me there is no difference between a random spammer who wants to sell fake viagra and Greg from blahblah app, who wants me to use his cloud-driven javascript thingy.
I believe there is a role missing, in the view on customer relationships. Just because I am looking at things in your store doesn't mean I want to be treated as a customer already. I believe there should be a differentiation between somebody who already bought something and somebody who is about to. Aggressively sending email at any chance isn't the way to make this transformation, imho.