Re:TLS Everywhere, not https: URIs (2015)
by michaelt on Monday August 08, 2016 @05:34AM
(#12246459)
I've seen quite a bit of criticism of it for mail servers [1] because an attacker can simply block the 'STARTTLS' message and (many) clients will silently accept that.
[1] https://www.agwa.name/blog/post/starttls_considered_harmful
The main problem is preventing downgrade attacks. With mail it is easy to just remember the setting for every server. Not so with websites.