What is the safest free email service available to the public?

According to me it is GMAIL .

First it will never ever go down as powered by the king of web, Google
Second hacking Gmail is Infact impossible, many hackers seriously try forgot password but in Gmail if you dont have mobile or alternate email you have to verify your self by CREDIT Card. 

Govt Agency also can not view these email as they are encrypted over 128 bit or 256 bit encryption

One Incident:
Once there was a virus which was decrypting HTTPS protocol messages , google was the first one to recover over this issue.

But one thing is there about gmail is that algorithms of GMAIL read your email for showing up advertisement (Outlook do not read your email)