If I type 'l~hsmtp.gmail.com' into mutt while my Debian folder is open, it finds "Msgs:245/1671". The tip of an iceberg of people who would be happy to use a mail client that's free software, if there was one that met their needs ...
The campaign is at 13k right now after 5 days. Hopefully now that it's taken off to some extent it'll get enough publicity to ramp up slightly, which would let it succeed. It would be sad to get to 80k and fail -- and these campaigns typically have a dip in the middle.
I do wonder how long a release cycle is. Is this paying for 3 months, or a year or what? Given that they're in SF, my guess would be toward the short end, which is a pity. Different living situations can stretch a minor 25k croudfunding success into a much longer opportunity to Get Things Done. My experience is, it's awesome when it happens.
I don't think that their stated goals match up with 100K worth of work, but I suspect that with that much effort they will actually get a lot more done than the small amount they have listed.