Within the O365 Encrypt drop-down menu (mentioned in the “How to Encrypt an Email” section of this documentation), users are able to disable the ability to forward an email. This feature can prevent emails with sensitive content being forward to individuals outside of the intended recipient(s).
What the “Do Not Forward” Feature Does
The Do Not Forward feature prevents sent messages from being forward to others outside of the recipient(s), adding an extra layer of security to email messages.
How to Mark an Email as “Do Not Forward”
To mark an email as Do Not Forward (and revoke the ability for the recipient to forward your message), follow these steps:
In the message to be marked Do Not Forward, select the Options tab at the top of the message window
In the Options bar, click the downward-facing arrow under Encrypt
Select the appropriate mailbox from the dropdown menu that appears (if applicable)
In the menu that appears, select Do Not Forward
How to Tell an Email is Marked “Do Not Forward”
There are multiple ways to determine if a message is marked as Do Not Forward:
When previewing the message that is marked Do Not Forward a message stating that the sender has sent a protected message will be displayed.
When reading the message, at the top of the message pane, the following message will be displayed: “Do Not Forward – Recipients can read this message, but cannot forward, print, or copy content. The conversation starter has full permission to their message and all replies.”