Error replying to externally encrypted email: "Microsoft Outlook was not able to create a message with restricted permission"

Symptom: When replying to an email in Outlook for Windows that was sent from an external sender, and they have encrypted the email, you receive the following error message –

“Microsoft Outlook was not able to create a message with restricted permission.”

Workaround: This issue is currently only affecting the desktop version of Outlook (Outlook for Windows). Replying from Outlook for iOS (on your iPhone) or Outlook on the web (OWA) is NOT affected by this issue. So, as a workaround, please reply to any affected encrypted external email by using either your iPhone or Outlook on the web.

To access Outlook on the Web from your laptop, in Outlook, simply click on the File menu, then under Account settings, click the link to “Access this account on the web”, as shown here -

The link is - https://outlook.office365.com/owa/ssyaf.org/

Login with your SSYAF credentials, and you can then access and reply to the affected email from your browser.