[Drip33]

There's a lot they can do, but then it makes it impossible to search your inbox for old emails by subject, from, to etc fields.

You can reduce what an adversary sees by not including anything useful in the subject line and the only thing you can't protect is who you're speaking to and when.

[gruez]

The third party doctrine[1] allows the government to access your call records (and other metadata) without a warrant, but I don't think anyone's fine with that.

[1] https://en.wikipedia.org/wiki/Smith_v._Maryland