To me, this problem can be solved on a purely philosophical level. In other words, before delving into the technical aspects, one must address the fundamental question: “Do we want to encrypt as much as possible or not at all?”

At first, the argument in favour of maximum encryption may seem compelling. However, upon closer inspection, it falls apart. Essentially, it only makes it harder to read your correspondence for those who give up early. Meanwhile, determined parties, such as large organizations and state actors, can still easily read your correspondence even with this type of encryption scheme.

You might ask yourself, “But Mozilla told me that they would try to encrypt as much as possible!” Instead, the fact is that sometimes they will also have to forgo encryption, because the scheme can only encrypt most of the time. And it’s in those instances that determined parties strike!

As such, this kind of “encryption” scheme really only serves to lull people into a false sense of security, and that is often more dangerous than simply letting people know that their e-mails aren't encrypted at all.

So, for those of you who are inclined to believe in conspiracy theories, the real issue is not that e-mails have remained unencrypted until now. Once you understand that your e-mails are sent in the open, you can take appropriate precautions and avoid sharing sensitive information through e-mail. Meanwhile, if you think that your e-mails are confidential, you might be more inclined to let slip important secrets, when it’s actually being fully disclosed to any determined third party.

The false maxim is that more encryption is better than no encryption. Meanwhile it does not follow that more encryption equals more security or better confidentiality.