I've been using Rackspace mail for a few years now, flawless service and shockingly good customer support - helpful, competent people available instantly, cannot recommend enough. Given our email accounts our the skeleton keys of our digital lives relying on a free service, or even a paid service where support is something the company sees as a numbers game seems madness.

My only gripe is the lack of support for two-factor authentication, apparently this is under development currently.