Different use cases require different tools. As an advocate of Tor, i2p, and similar privacy/anonymity preserving tools it speaks volume that if I don't have i2p mail it's not likely something your going to be able to get even a minority of technical users to adopt. No, first self-host via an easy to adopt solution and help undermine an abusive government's efforts to access any and all mail through dubious legal processes such as those used against Lavabit. The government went after Lavabit's private keys, not just Edward Snowden's email account. The government wanted access to all mail. This can be hindered by self-hosting your own mail.
It's also ideal for more users to adopt Thunderbird and GPG encryption. The FSF has a great guide on this here (not that I am anticipating mass adoption, but it's worth using since you don't want to stand out when you actually end up needing it):