I'm reminded of Andrew Chen's post on Facebook DAU/MAU number <a href="http://andrewchen.co/2012/05/16/quora-has-facebooks-daumau-always-been-50/" rel="nofollow">http://andrewchen.co/2012/05/16/quora-has-facebooks-daumau-a...</a><p>Part of the reason that email is so sticky is that it has an incredibly high DAU.