If you have installed the necessary plug-in, when you want to send something, there is a small toggle switch on the top of the compose screen (if you are using webmail in Firefox or Chrome or its plug-in on Outlook). Turning that on will bring up a "send secure" button to encrypt your message. There are tool tips that appear as you hover over the various options with your mouse, a nice touch. These include the ability to add an unencrypted introductory message that will introduce your recipient to the context of the message that you are sending, and why you want to encrypt the remainder of the message. You can also set when your message will expire or disable any forwarding for additional security.
Virtru also supports zero knowledge encryption, although it adds a separate activation step when a new user receives the first encrypted message.
One other caveat: attachments are limited to 25MB, which could be an issue for some users who want to send bigger files. Another issue: Virtru won't protect you from the Silk Road scenario where someone grabs your phone or laptop while your email is open, because the decrypts happen automatically.
Despite these caveats, we think Virtru has some very nice options, and given it was the least expensive of the seven products tested, it is definitely worth a closer look.
Virtru has a free version, and a pro version that will cost $2.50 a user per month, with a discount for annual purchases. Both are available for 14-day free trials. The free version just does encryption without the additional features such as message expiration and domain administration that are found in the paid Pro version.
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