Now, that doesn't change the fact that Yahoo rolled over like a puppy when the government came calling, which is reprehensible for any tech company to do. They should have fought it and asked for a warrant for the specific persons of interest, rather than happily fucking over every single Yahoo email subscriber.
SMTP was designed with no privacy, security, reputation, or authentication capabilities. Even the add-ons which provide some of these (e.g., PGP -- and I'm looking for the comment on this thread mentioning that) doesn't address what's almost always more useful than full-text search: metadata.
It's the systematic failure of tech industry leadership to come up with an open and viable alternative to email that's landed us in this position, and that's a lack of action that's increasingly utterly indefensible.
[1] https://www.google.com/transparencyreport/saferemail/faq/#wh...
[2] http://arstechnica.com/tech-policy/2016/10/report-fbi-andor-...
Concepts of scale and intent are rather central to this discussion.
This isn't about a postal employee glancing at your postcard and thinking you must be having a nice vacation.