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

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

A new Microsoft-issued software patch for Outlook (Classic) on Windows 11 inadvertently broke encrypted email support - ...

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 ...

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