Open Terminal by using one of the following methods: For information about this update, see MS16-070: Description of the security update for Office 2016 for Mac: June 14, 2016. If your Outlook installation is not at version 15.23 or a later version, install the June 14, 2016, update for Outlook 2016 for Mac or a later update.
Step 1: Check the Outlook for Mac version number Then, disable the preview feature for encrypted email messages by running a command in Terminal. To fix this issue, update Outlook 2016 for Mac to version 15.23 or a later version. In Outlook 2016 for Mac, when you navigate to a folder in which several encrypted email messages are displayed in the message list, Outlook freezes or experiences other performance issues.
