Hello JG
Yes, you can enable external email tags via Windows PowerShell by typing the following lines and pressing Enter: `Set-ExternalInOutlook -Enabled $true`. Then restart your PC and check Outlook after 24-48 hours to see if the External warning tag or label appears¹.
However, external tagging is disabled by default, so you may connect to Exchange online PowerShell and run the command `Set-ExternalInOutlook –Enabled $false`².
There are multiple ways to add [External] tag to emails received from outside the organization. You can apply [External] tag using transport rule in Exchange and Office 365. You can also set up [External] tag using rules in your third-party gateway³.
I hope this helps!
Source: Conversation with Bing, 4/16/2023
(1) How to Remove The External Tag/Label in Outlook - Windows Report.
https://windowsreport.com/outlook-external-tag-remove/.
(2) Outlook External Email Tag - Microsoft Community.
https://answers.microsoft.com/en-us/outlook_com/forum/all/outlook-external-email-tag/726edfb4-fd09-4....
(3) Users cannot see [External] tag in OWA and Outlook Conversation View.
https://techcommunity.microsoft.com/t5/exchange/users-cannot-see-external-tag-in-owa-and-outlook-con....
Hope this help