Virtru - Virtru is your data privacy force field, wrapping and protecting emails and files wherever they're shared. Easy-to-use data security software for business. People also askIs Virtru Hipaa compliant?

Polymail - Native email app for email productivity.

NeoCertified Secure Email - NeoCertified is a solution that provides secure email encryption for businesses and organizations across all industries, including healthcare, finance, legal, non-profit and education.

Airmail for iOS - One of the best Mac email clients, now on iPhone

Encyro - Use Encyro to send sensitive messages and files to your customers and service providers, including accountants, loan officers, health coaches, and others. Stay organized and forward documents from your mobile device.

Airmail - Airmail is a lightweight and lightning fast mail client for Mac.