Roundcube - Web-based IMAP email client
Smart HTTPS - Automatically changes HTTP addresses to the secure HTTPS, and if loading encounters error, reverts...
Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.
SSL Enforcer - SSL Enforcer - Force SSL/TLS encryption for any browser or app. Block all unsecure connections.
Mailpile - Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.
KB SSL Enforcer - This extension enforces encryption for websites that support it as much as currently possible in...