[Environment]
Any Samsung Knox 2.0+ mobile device using the default native email client

[Issue]
Knox email notifications do not show any content, even if device notifications are enabled to show content on the lock screen. However, Outlook and Gmail notifications will still show content.

[Cause]
By default, content is hidden for Knox Workspace notifications. This is to make sure no one can read, record, or otherwise access the content of email notifications coming from your secure Workspace container. 

[Resolution]

If you'd like to to unhide the content for Knox Workspace notifications, you can change the setting on your device via Workspace settings > Notifications & data > Show notification content. Workspace settings can be accessed inside the Knox Workspace. You can only change the setting if your IT admin has allowed users to do so. 

For IT admins:
You can allow or disallow users to change the "Show notification content" setting through your EMM/MDM. Note that not all EMMs/MDMs will allow you to do this.