Mail

   smtp-tls-checker – check an email domain for SMTP TLS support.
   MX Toolbox – all of your MX record, DNS, blacklist and SMTP diagnostics in one integrated tool.
   Secure Email – complete email test tools for email technicians.
   blacklistalert – checks to see if your domain is on a Real Time Spam Blacklist.
   MultiRBL – complete IP check for sending Mailservers.
   DKIM SPF & Spam Assassin Validator – checks mail authentication and scores messages with Spam Assassin.

Secure Webmail Providers

   CounterMail – online email service, designed to provide maximum security and privacy.
   Mail2Tor – is a Tor Hidden Service that allows anyone to send and receive emails anonymously.
   Tutanota – is the world’s most secure email service and amazingly easy to use.
   Protonmail – is the world’s largest secure email service, developed by CERN and MIT scientists.
   Startmail – private & encrypted email made easy.