In the press, I often read of the potential for state actors to intercept and record email via man-in-the-middle attacks. For example, the large data storage facility in Utah being built by the NSA right now is alleged to be stored "the complete contents of private emails" right in the wikipedia article (as linked).
However, I am wondering how true this really is. As I understand most email servers these days use SSL or TSL to send all their traffic encrypted, so if, say, Verizon or Comcast users are having their emails being transported routinely by SSL/TSL, how could the NSA be getting the clear text? It sounds kind of unbelievable or exaggerated to me. Sure, if somebody sends the email via telnet it can be recorded, but most emails are sent secured.
In fact, last year at SIGCOMM researchers presented a paper examining this exact question (see Durumeric, Adrian, et al, SIGCOMM 2015) and they report that in excess of 80% of email traffic is routinely sent via TSL or other secure protocol.
So, is the whole email surveillance thing exaggerated or is it for real?