How do I open a protected message? - Microsoft Support
If you receive a protected email message sent to the work or school account you use with Microsoft 365 in Outlook or Outlook on the web, the message should open like any other message. You'll see a banner at the top of the message that informs you of any restrictions on the message.
Applies To:
Outlook for Microsoft 365, Outlook 2021, Outlook 2019, Outlook 2016, Outlook on the web, New Outlook for Windows, Outlook for Android, Outlook for iOS