Private-Mail is an email provider that encrypts your inbox, files, and uses OpenPGP to encrypt your emails. Although limited and lacking some of the features of the paid packages, Private-Mail offers an entirely free plan that you can use forever. If you don't value features like calendars or a taskbar, and only want a private email with straightforward encryption, the free plan will suffice. However, it's important to bear in mind that the free option only gives 100MB email storage, plus another 100MB for file storage.
Private-Mail lets you easily set up OpenPGP encryption so you can communicate privately for free.