External Email Tagging In Exchange Online

Microsoft has released a new feature to make it easier for organizations to flag external emails to the users. Companies have been creative in the past to accomplish this task by using transport rules.

I am sure all of you have seen these banners, in all colours & design over the years to flag internal users that the email that they have received is from an external user. A sample one is given below.

We have a new way of flagging external emails without a banner now in Exchange Online. The sad part is that it is only available in Outlook on the web & Outlook mobile at the time of writing. The feature is still in the kitchen as far as Outlook for Windows is concerned. This means that we still have to run this colourful banner for a while, to cover all ways by which an end user work with an Exchange Online mailbox.

External email tagging is disabled by default in the tenant. Run through the below steps in order to enable the feature.

Login to Exchange Online using PowerShell.

Run Get-ExternalInOutlook to find the current state (it should be disabled).

Run Set-ExternalInOutlook -Enabled $true to enable the feature.

Confirm that the feature has been enabled by running the Get-ExternalInOutlook command again.

The ‘AllowList’ parameter allows you to add external domains & senders who you dont want to be flagged as external, maybe partner companies.

You can run the below command to add a few domains, so that they are not flagged as external.

Set-ExternalInOutlook -AllowList @{Add=”cloudiffic.com”, “microsoft.com”}

You can remove the domains the same way.

Set-ExternalInOutlook -AllowList @{Remove=”cloudiffic.com”, “microsoft.com”}

Once the changes have been made, it takes anywhere between 24 to 48 hours as per Microsoft documentation. In my tenant, the feature was lit up in a few hours.

The external tagging in Outlook on the web appears as below.

Outlook Mobile has the same look and feel as well.

Once the external tagging is available in Outlook, we can safely remove the good old banners!