Netscape 4.0 was not my fault. During that dark period, I worked with Lisa Repka on S/MIME, Netscape's implementation of the then-new standard for cryptographically secure email. At the time, I was very glad that we managed to ship this before the U.S. Government had gotten around to making it illegal for us to do so. (And yet, all these years later and still nobody ever encrypts their email...)
This makes me wonder, why don't mainstream email clients (Apple Mail, Thunderbird) encrypt our mails by default?