On Wed, Jun 30, 2004, John Levine wrote:
MTA. If people were going to use TLS certs to authenticate their
mail channels, they'd be doing so already, but they're not.
It's hard to do that with the hierarchical structure of X.509 unless
you are a commercial entity and you want to pay money a certain
company.... I exchange CA certs with some people (and enforce
authenticated mails) but it's a bit ugly to maintain.
There was a draft that described using the OpenPGP trust structure
("web of trust") which unfortunately didn't lead to an implementation.