Virtru users should be aware that forwarding an email when Virtru is turned on will have different results depending on the way the mail was forwarded and how it will be read. The following scenarios exemplifying this are taken from the Virtru KB article Forwarding with Virtru.

Secure message is forwarded without Virtru enabled:
Without Virtru encryption enabled while forwarding, the new recipient cannot be added to the existing secure policy and will not have access to the content.  The new recipient needs to be added to the secure policy so that the original recipient can monitor to whom the email was forwarded, and revoke access if necessary.  

Secure message is forwarded with Virtru enabled to a non-Virtru using recipient:
If a secure message is forwarded - with Virtru encryption enabled - to a recipient who reads the email in our Secure Reader, the new recipient can only view the latest entry in the thread.  The Secure Reader does not support full threads and will instead show the message "This email chain has been secured by Virtru."

Secure message is forwarded with Virtru enabled to another Virtru user:
If both the forwarding user and the new recipient use Virtru, the new recipient is added to the existing secure policy and will have access to the entire forwarded thread.  The original sender will be able to see that this message has been forwarded by checking the forwarding tree in the Virtru Dashboard, allowing the revocation of their message.

Readers should also note that the feature called "disable forwarding" in Virtru does not prevent someone from forwarding an email. Instead, the email can still be forwarded, but additional recipients will be unable to decrypt it. See the IT KB article Prevent Forwarded Email from Being Read with Virtru for more details.