Emails are easy to access and simple to copy. So if you want to protect your emails, you must learn how to encrypt them.
A particularly popular one is PGP or its Gnu offshoot GPG. It does this by encrypting your mail so that no-one but the planned person can read it. When encrypted, the message is like an incomprehensible jumble of random characters. PGP has proved itself quite able of resisting even the most up-market forms of research directed at reading the encrypted text.”