New guide on email

This is a proposal to take out the information on email from the guide on private communications and to reorganize it so as to have a new guide on email with the following table of content:

• What is an email and how email works
  • just a non-encrypted text file copied on several servers
  • beyond the body: what's in a header and what to look for in a header
  • difference between mail service and mail client (issue #186 (closed))
  • difference between POP and IMAP
  • TLS - how to check
• How to create a mail account
  • how to choose a mail provider, based on different needs
  • how to choose a user name
  • pros and cons of reading mail through a browser, a client or an app
• Basic email security
  • using an alias and making sure the header isn't revealing your primary address
  • disposable email
  • encrypting email
  • deleting old messages
• Advanced email security
  • using a VPN to create an email and protect your identity
  • anonymous remailers