IMHO, anyone who claims to care about privacy should seriously consider throwing down the ~$10 a month (I forget exactly how much it costs) to have a paid PM account. The company isn't perfect, but it's a far sight better than the majority of other providers out there. Furthermore, by paying for your account you are not only directly supporting a service that aspires to provide communications privacy, you're also helping to subsidize said service for those users who may not be able to afford a paid account (particularly important in countries where economic and governmental problems overlap).

I pay for my PM account and have had nothing but good experiences with the company and service so far (including with the VPN and with the mobile app before I ditched my iPhone). It took me years to migrate off of Gmail but since I finally managed to do it I've never looked back. Give it a shot.