I have a subset of users experiencing this issue. They are standard, internal employees. Whenever they compose a new email message and apply an AIP policy to the new message (whether a custom policy or a default template like 'Do Not Forward') the message body is erased and replaced with the following text after the message is sent:
"This message is protected with Microsoft Information Protection. You can open it using Microsoft Outlook, which is available for iOS, Android, Windows, and Mac OS. Get Outlook for your device here: https://aka.ms/protectedmessage.
Microsoft Information Protection allows you to ensure your emails can't be copied or forwarded without your permission. Learn more at https://microsoft.com/rms."
The original content in the message body is removed. If we look at the user's sent folder, we see a sent email with the AIP Informational text, and not the message that was in the email prior to the user pressing "send." Has anyone seen something similar or have an idea what might be causing this behavior?
I have not heard of this issue before and cannot find an example of this happening when searching for similar issues.