- Load the exchange online module on PowerShell.
Click here to know more - Turn on external tagging.
The following command will enable external tagging for the whole organization.
Set-ExternalInOutlook -Enabled $true
You could also omit senders and domains from the external tagging feature.
For example, to omit admin@contosso.com, I would enter the following:
Set-ExternalInOutlook -AllowList admin@contosso.com
To omit the whole domain
Set-ExternalInOutlook -AllowList “microsoft.com”, “apple.com” – Enabled $True