This seems to be a the type of comment that is catchy, but in truth mostly vacuous. How does one have a 'Draw Something' of email? There is no sticking power to most games. There are high switching costs (in terms of time, productivity, etc.) when it comes to e-mail. Hell, I used Yahoo Mail for years after Gmail came out because I wasn't used to its interface. If Mailbox has managed to get people to switch to their app, it is likely that they will continue to use the app... Not drop it in three months like people did with Draw Something.