It mostly started happening after Mailbox's waitlist of hundreds of thousands and subsequent buyout from Dropbox during the wait list period.

I saw this article this morning and it made me raise my eyebrows: http://www.businessinsider.com/the-league-app-has-a-75000-pe...

A waitlist isn't inherently impossible for startups; I'd expect a few hundred at most, but 75,000?

EDIT: All email clients have the same name. :p