Maybe I don't want every ISP between you and me knowing which non-profits I choose to donate to(*).

In general, emails should be encrypted unless there's a very good reason to leave them in cleartext.


(*) What if the next presidential administration really dislikes the organization I donate to and directs the IRS to track down everybody who has ever donated to them and hit them with tax audits? That would never happen in a free country though, right?