Outlook Update Breaks Encrypted Emails for Windows Users

Windows users are facing a new problem with Outlook (Classic) after a recent Microsoft update. The latest patch, build 19426.20218, has caused encrypted emails to stop working for some users. Microsoft has confirmed the issue and is working on a fix.

What Users Are Experiencing

After updating Outlook on Windows 10 or Windows 11, some users cannot open emails sent with the “encrypt only” setting.

Affected users report seeing an error message in the Reading Pane, stating the email cannot be opened until credentials are verified.

If users try opening the email manually, Outlook generates a blank attachment called “message_v2.rpmsg”, which cannot be read inside the app.

Microsoft Confirms the Bug

Microsoft acknowledged the problem on its official support website. The company stated the Outlook team is actively investigating and will release updates when a permanent fix is ready.

Currently, no permanent solution is available.

Temporary Workarounds

Microsoft has shared a few temporary fixes:

1. Change Encryption Settings

   • Go to Options in Outlook’s ribbon.

   • Select Encrypt → Do Not Forward.

   • This may allow users to open some encrypted messages.

2. Revert to Previous Version

   • Close all Office applications.

   • Use an elevated Command Prompt to roll back Outlook to a version before build 19426.20218.

3. Other Interim Solutions

   • Microsoft has provided a third workaround in support documents, but all options are temporary until the official patch is released.

This bug mainly affects business users and organizations that rely on Outlook’s encryption features for sensitive emails. Users are advised to avoid the latest update if encrypted emails are critical to their workflow.