What are some alternatives?
When comparing Zix and Virtru, you can also consider the following products
Microsoft Exchange - Secure Email Gateway
Symantec Data Loss Prevention - Fully protect your data with the comprehensive detection technologies and unified policies of Symantec's industry leading Data Loss Prevention (DLP).
Mimecast Secure Email Gateway - Prevent targeted email-borne attacks with Mimecast Secure Email Gateway for cloud-based anti-virus and anti-spam protection.
Microsoft BitLocker - BitLocker is a full disk encryption feature included with Windows Vista and later.
Barracuda Email Security Service - Secure Email Gateway
OpenSSH - OpenSSH is a free version of the SSH connectivity tools that technical users rely on.