Part of the problem is that we've outsourced responsibility for e-mail to third parties, which has placed those third parties in the difficult position of deciding whether to fight the impossible battle on your behalf, or just submit to the inevitable.
Running your own mail server, however, neatly deals with the problem of the ECPA and the 6 month rule. Warrant, no warrant, new, old, whatever, if they want access to e-mail on a server you own, you're going to know, and you will have the opportunity to fight it. It is easier than ever these days to run your own mail server, if you wish.
Since the mail host is the most attractive target, you can run your own. Some of the better NAS products come with mail capabilities, such as Synology, and Apple's OSX Server features mail server capabilities as well.
Using encryption such as PGP can protect mail crossing the public Internet, which is the next weakest link.
Neither of these is going to absolutely stop the government from knowing something about what you are doing, but you can simultaneously make it more difficult for them while also eliminating the chance that your e-mail provider will go out of business for some random reason.