What is External email Tagging?

External email tagging means that messages received from any domain except those registered for the tenant are marked by Exchange as “external” when they pass through the transport service on their way to user mailboxes.

In addition to the tag, when a message is read, the user is offered the chance to block the sender.

How to activate External Email Tagging?

External tagging is disabled by default.  In this instance, you’ll have to run the Set-ExternalInOutlook cmdlet to get things moving.

• Connect to the Exchange Online Management endpoint (or use remote PowerShell if you must).
• Run Set-ExternalInOutlook to enable external tagging. (You can exclude certain domains or individual email address depending on requirements.)

For example: I want to exclude “Microsoft.com”. So, we need to run the below command.

       Set-ExternalInOutlook -AllowList “microsoft.com” -Enabled $True

• You can add more domains or individual email address in allow list. Below is the command.

Set-ExternalInOutlook -AllowList @{Add=”techienetworks.com”}

• To see the tagging configuration run Get-ExternalInOutlook

After that, it’s a matter of waiting for Exchange Online to acknowledge the configuration update and enable tagging. Microsoft says that activation should happen within 24-48 hours.