If it had 2 factor auth and a way to trust a particular machine or application (which I think it does?), SMTP and IMAP were free (are they? used to have to pay), there were no ads (even though GMail's aren't terrible), and it guaranteed it would not delete my account or email if unused for years, if it guaranteed a better uptime than GMail (which is already good enough), had contact dupe fixer as good as or better than GMail, had plugin for Thunderbird, etc. to keep contacts in sync so didn't have to use a 3rd party free plugin that breaks at times, and I could see that it was easier to use than GMail, and they guaranteed great security (better than GMail) and that they didn't ever look at the content of my mail or my contacts, that they would never sell me out to anyone, that they were as conspiracy-conscious as I was and apolitical, and if it allowed clutter-free integration with Facebook, etc. to mine them for email addresses when I connected to someone, and if they hated spam and would help me organize my life with easy calendar integration to every major smartphone and other devices, share calendar only with family or have other calendars to share with diff groups, get things done without integrating a tasklist, and ignore the stupid stuff, and guarantee email for life, then I might use it.