There may be explicit laws for wiretapping phones, but the expectation of privacy in email does rest on the 4th Amendment. Here's an example of a ruling on emails that are held by a 3rd party:
So there does seem to be a weird double standard in the "3rd party doctrine" between content and routing information.
I think if you asked 100 people on a random street what part of email they expect to be private, almost everyone would answer "all of it." I agree with the EFF that the Smith ruling is outdated.
https://www.eff.org/deeplinks/2010/12/breaking-news-eff-vict...
So there does seem to be a weird double standard in the "3rd party doctrine" between content and routing information.
I think if you asked 100 people on a random street what part of email they expect to be private, almost everyone would answer "all of it." I agree with the EFF that the Smith ruling is outdated.
edit: clarity