It sounds like the Sparrow guys ran out of money and were bailed out by Google. This is a sad outcome, but not unexpected: plenty of people make "good enough"

It sounds like the Sparrow guys ran out of money and were bailed out by Google. This is a sad outcome, but not unexpected: plenty of people make "good enough" mail clients and give them away for free. Just because you want a gold-plated email client doesn't mean many other people are willing to pay for it, and monetizing an email client is very difficult without massive scale, and advertising.