Earlier quoted context omitted.
Probably because there simply isn't money to be made in being an e-mail startup. Or, more correctly, there isn't enough money to be made to satisfy VC investors. Mailbox and the like could have lived quite comfortably as paid-for apps with comfortable but small levels of profit, but that isn't what Silicon Valley rewards. EDIT: also, IIRC Apple's restrictions on background processing meant that they needed to have ev…
> there isn't enough money to be made to satisfy VC investors. Mailbox and the like could have lived quite comfortably as paid-for apps with comfortable I'm not sure that's true (see: Sparrow). I just don't think there is enough demand for people to want to pay for an email client. I imagine for a huge majority of people, default mail client's work fine enough for personal use.
Part of the problem is, unlike say Pinboard, an email client doesn't feel like 1-3 devs worth of work. The protocols are horrendous, you have to understand the quirks of lots of servers, etc. Plus all the UI and backend and search work. I'm not sure it's approachable as a small indie company.
There's also, of course, bad behavior by large companies such as mozilla: Thunderbird made it very difficult to build an indie email client because you have to compete on merits and against free, but they eventually got bored and just quit making it. Not to mention competing with free/ad-supported. And the semi-annual YC/vc supported email client company.
Not to mention what is coming close to active sabotage of productivity apps by the ios and mac app stores (lack of trials, lack of upgrades, etc).