Cryptzone

Cryptzone has loads of features, one of the most widely recognized perhaps being the app security. However, when talking about emails specifically, most impressive is the integration with both Office Suite and SharePoint, all of that dynamically and easily. Powerful options like regulating who can access your file, tracking access and preventing delicate information from getting to wrong hands makes it extremely powerful tool for any organization.

Perhaps the only negative aspect I can think of is the pricing, especially as there is no trial version available which means you can't really give it a try and see it functioning for you on a daily basis - while many other similar solutions enable such option. Therefore, you are kind a in a tough spot when thinking of getting a decent encryption tool.

The main aspect making Cryptzone still one of the finest solutions for securing documents is the full compatibility with Office 365, meaning you can secure delicate documents right after creating them. This and many other security options makes it a go-to tool, even if there is no trial - you can always request for a demo!