All e-mail services are by their very nature insecure. Email privacy is a problem that disturbs email users if sensitive information is to be sent. Yes, major and medium-sized businesses take precautions to ensure that their e-mail systems are secure. You do it by developing and installing your own email services. Nobody with Gmail or Outlook or any other free email provider can fathom any critical government agency or defense force sending private communications. Nothing that you send using free e-mail is safe unless you take extraordinary safeguards. Yes, the application for encryption may be obtained and your emails encrypted. However, you must then request that your email recipients install the same services to read and react to your emails.
Some companies employ popular free, yet encrypted email services. It's a cheaper way to upgrade your email service providers' malware attack security while encrypting their emails at the same time. People will not quit using free email services like Google and Microsoft, but they may take steps to preserve their privacy.