External tagging has been available for OWA, Outlook mobile, and Outlook for Mac since 2021. Now it’s coming to Outlook for Windows. Some might wonder about why it’s taken Microsoft so long to add external tagging to the Windows client. It might be that they’re waiting for the Monarch client, but it’s more likely the difficulty of retrofitting new features into the Outlook GUI.
https://office365itpros.com/2022/10/06/external-tagging-outlook-windows/
