Classic Outlook tells you to open the email to "read its contents and verify your credentials," but that doesn't work.

The problem happens for users who encrypt the email using the settings under the email File dialog (File > Encrypt), ...

Microsoft has confirmed a known issue that prevents recipients from opening encrypted emails in classic Outlook.

In the latest version of classic Outlook, users can't open encrypted emails. Microsoft confirms the issue and is investigating.

You may see this error because the Microsoft 365 encryption service cannot verify your identity or check if you have permission to view the message. This is not ...