Well, that's another type of error (human error). And TLS will not address that type of error either.

I was referring to the case where the email is redirecting to (or through) an unintended recipient.

Before my comment is further misinterpreted, let me make clear:

I am not saying "Do not use SSL/TLS." By all means use it; regardless of the bugs, the complexity and the lack of an acceptable authentication mechanism.

But encrypting before transport is even more important, IMO. And so that is a more interesting statistic.

The two are not mutually exclusive.

Not to mention one could use SSH for encryption "in transit". It has better authentication than SSL/TLS, but that's only my opinion.