Are you in a position that you need to send encrypted emails? Are you bound by certain privacy regulations when sending emails? Do you use Gmail and wish you could send encrypted emails right from your Gmail window? Guess what? You can.
Virtru which provides just this kind of service.
What is great about Virtu is that it is a an email add-on so you dont have to go to another site to send private, encrypted messages. Virtru works with Chrome, Gmail, Outlook, Yahoo!, Mac Mail, Android, iOS, and Google Apps for work. Virtru is a simple as flipping a switch.
Virtru provides a great overview of how it works right here.
Virtru offers two pricing packages. The Free service allows for End-to-End Email encryption and End-to-End attachment encryption. For only $2 per user per month you get the added features of revoking emails, control forwarding, email expiration, personal dashboard, HIPAA Compliance, FERPA Compliance, SLA support, and Team Administration.
I have had the opportunity to use this service and have found it to be very simple and user friendly.
Note: This is one of many services that provide this functionality. I am not affiliated with Virtru in any way. Virtru currently does not integrate with the new Inbox by Gmail.