Ive never realy been a big beleiver in "secure emails"
Every since Ive been on these foums I see it preached... No Yahoo,Opera, or Hotmail. Some sources for a few years would not even reply unless it was a hushmail. Like you pointed out Look how secure that ended up being.
Now I can Understand No Aol or Family emails..... I think you need something Atleast password protected to ONLY you, But other then that Unless your Using PGP
(The real kind thats hard as hell to figure out) I dont think as far as the free ones go theres any that are "secure".
I Look at it like a telephone. If they think your breaking the law enough that they want to read your email (Or Tap your Phone) They will do it.