Native external sender callouts on email in Outlook

[The_Exchange_Team]

Overview

We know that some of our customers leverage Exchange transport rules to prepend subject line or insert the message body to show the email is from external senders. This approach has a few limitations which we heard:

• You can end up with duplicate [External] tags in subject line if external users keep replying to the thread (some of our customers use customized solutions to remove the duplicates).
• Adding things to subject line breaks Outlook conversation threading, as the subject line is modified, so messages no longer “belong” to the same conversation.
• Changed subject (or message body) stays as a part of the message during reply or forward, which leads to confusion if the thread becomes internal.
• There can be localization issues, as transport rules have no knowledge of client language that end-users are using.
• Those additions might take a lot of space in the subject line, making it hard to preview the subject on smaller devices.

We have heard the feedback on this, and are working on providing a native experience to identify emails from senders outside your organizations (which can help protect against spam & phishing threats). This is achieved by presenting a new tag on emails called “External” (the string is localized based on your client language setting) and exposing related user interface at the top of your message reading view to see and verify the real sender's email address.

To set this up

1. Exchange Online tenant admin will need to run the cmdlet Set-ExternalInOutlook to enable the new user interface for the whole tenant (this is available now); adding certain emails and domains to the allow list via the cmdlet is also possible.
2. Outlook on the web already supports this. Outlook Mobile (iOS & Android) and Outlook for Mac are rolling out this feature. Specific versions:
   • Outlook on the web: available now
   • Outlook for Windows: Update 10/6/23: This feature is now available in Semi-Annual Enterprise Channel (Preview) too. External Tag view in Outlook for Windows (matching other clients) released to production for Current Channel and Monthly Enterprise Channel in Version 2211 for builds 15831.20190 and higher. We anticipate the External tag to reach Semi-Annual Preview Channel with Version 2308 on the September 12^th 2023 public update and reach Semi-Annual Enterprise Channel with Version 2308 with the January 9^th 2024 public update.  If any of the versions or dates change we will update this topic. See Update history for Microsoft 365 Apps (listed by date) to see release status of versions.
   • Outlook mobile (iOS & Android): version 4.2111.0 and higher
   • New Outlook for Mac: version 16.47 and higher

If you are using the prepend subject line transport rules currently to add an [EXTERNAL] tag in external email subject line: the new Outlook native callouts are adding a new MAPI property called IsExternalSender to the email item. Once all the (above listed) client versions you require have this functionality, to avoid emails being marked ‘External’ twice (once by new native functionality and once by the transport rule), please turn off the transport rule first before turning on Outlook native external sender callouts.

We tracked this feature in Microsoft 365 Roadmap ID 70595. This feature can be enabled on the tenant level now.

Outlook on the web, Mac, and mobile will display an External tag in the message list. Outlook Desktop and OWA will show the sender's email address at reading pane info bar. Outlook mobile and Outlook for Mac will only see an external tag on the message reading pane, and users will need to click the tag to see the real sender’s email address.

Outlook for Windows view of External sender (note that the experience is slightly different from others below):

Update 11/3/2022: The newer External Tag view for Outlook for Windows (matching other clients) is currently rolling out:

Outlook on the web view of External sender:

In Outlook for iOS, External sender user interface in the message list, External tag when reading chosen email and view of sender's email address after tapping External label:

Once this feature is enabled via PowerShell, it might take 24-48 hours for your users to start seeing the External sender tag in email messages received from external sources (outside of your organization), providing their Outlook version supports it.

If enabling this, you might want to notify your users about the new feature and update your training and documentation, as appropriate.

Let us know here if you have any feedback!

The Outlook Team

[peterkarpati]

I have never set up external tagging also get-externalinoutlook gives Enabled: false. Despite some of the external emails tagged as External some not in Outlook for Windows.

Any idea?

[Casper Frank-Stender]

@peterkarpati must be configured as a transportrule

[peterkarpati]

@Casper Frank-Stender Nope. Mail Flow rules is empty

[Andres Bohren]

@Casper Frank-Stender 

Works here with Outlook Version 2005 (Build 14021.20000) (Beta Channel)

[Andrew Suthanah]

@Andres Bohren I think you showed a screenshot of the warning that is provided when you forward or reply to an email that includes an external recipient. The thread is regarding the 'Warning' that is inserted before the subject line when an email is RECEIVED from an external sender. 

This is not available in Outlook for PC yet. It is enabled on a per tenant basis and currently applies to Outlook on the Web, Outlook Mac, IOS & Android only.

[Jason E. Heiser]

After a couple of months of availability, where do we stand on creating exceptions by IP range and increasing the max entries beyond 30? With all of the Microsoft sending addresses I suspect some customers may be beyond 30 for M365 alone!

[cbron]

This feature is still not working in the Windows desktop version of Outlook. It works on Outlook for Android and Outlook on the Web though. This is the desktop version of Outlook I am running.

Microsoft® Outlook® for Microsoft 365 MSO (16.0.14026.20202) 32-bit

What version does it allegedly work on?

[tomrb08]

@benoitrando You need to use the following syntax for Allow List. 

Add or remove specific domains to Allow List: Set-ExternalInOutlook -AllowList @{Add="admin@cohovineyard.com"; Remove="admin@fourthcoffee.com"}

Set-ExternalOutlook Syntax 

[A-Rex]

Dear @The_Exchange_Team 

When will this feature be available for Outlook on Windows. As it's stated by the previous comments, this feature is still not in place yet (Outlook Version 2106 Build 14131.20278) but it is for any other platform. Please provide us with further info.

Many thanks.

Arbër

[alex_ha19]

not even in 2106? Wow ok :(

[dhruv9211]

@alex_ha19 Even in the latest build of outlook for windows it's not showing up.

[Andres Bohren]

@A-Rex @alex_ha19 @dhruv9211 

Please make sure, the Exchange Online Administrator did activate this Setting

Set-ExternalInOutlook -Enabled $true

Works for me on Microsoft 365 Apps for Enterprise since Version 2005 (Build 14021.20000)

Regards

Andres

[alex_ha19]

Yes its enabled. It works on Outlook mobile and OWA, but not on Windows

[Victor Ivanidze]

I can confirm - the feature does not work on Outlook for Windows

(Microsoft® Outlook® for Microsoft 365 MSO (16.0.14131.20278) 32-bit).

[alex_ha19]

I opened a ticket about this.

[Kevin Taber]

For those of you still trying to see this in Outlook Desktop… it’s not yet rolled out to the non-Beta channels. No sense opening tickets. The roadmap link in the article will show you that it’s still in the Development phase.

[Aragorn]

Outlook Version 2105 Build 14026.20334 (64-bit) still no show. Roadmap states July release? Hoping this will come soon.

[alex_ha19]

MS Support said that they have no ETA for this to be available on Outlook (Windows)
As mentioned also by @Kevin Taber  its only available for Insiders as of now.

[A-Rex]

The Roadmap states - Release July CY2021 - now i'm on Version 2107 and still nothing. Let's hope it gets published the coming days.

[cbron]

The Roadmap has been changing though. It originally read May 2021, even well into June. Hopefully the date won't slip yet again.

[sbradbury]

It's really annoying that this doesn't work in Outlook on Windows yet.

[sicoss]

Just started to see this now in Outlook running on Windows, seemed to go live today for me. I'm on 16.0.14228.20200 Microsoft 365 MSO, version 2107 build 14228.20204

[tomrb08]

I'm guessing this is the notification. Not very obvious considering what it's supposed to be doing. 

I'm on (16.0.14228.20200) 64-bit. 

[cbron]

Interesting. I'm on (16.0.14131.20278) 32-bit and still no notifications.

[A-Rex]

@tomrb08 yes, this shows up in my outlook too, but not the Tag. Microsoft postponed once again https://www.microsoft.com/microsoft-365/roadmap?filters=&searchterms=70595

[sicoss]

Yes sorry, I'm getting the mailtip about them being an external sender, but not the tag in the inbox next to the subject. So I've kind of got some of the functionality! And it's just on that version I quoted, when I log into an older version of Outlook I don't get that mailtip.

[tomrb08]

@sicoss @A-Rex I'm waiting for the Inbox tag as well. I saw the little "info" tag in the preview pane and was hoping that wasn't their idea of a tag.  It looks great on Outlook mobile and I'm hoping it's as obvious on desktop.

[Victor Ivanidze]

Hi @tomrb08, you can try to use this freeware: https://www.ivasoft.com/tagexternalflow.shtml. 

TagExternal does not change the subject line and body to mark a message but assigns a special category to a message.

[talbrechtsen]

Is there a way to deploy this to only certain users or groups for testing purposes? Or a way to easily disable this feature after deploying?

[A-Rex]

So now it has been published, Outlook is updated and see there, nothing. In the Update description on the roadmap site it does not mention the Windows Version of Outlook but in the Tags it mentions Desktop. I'm really confused now @The_Exchange_Team.

Version 2109 (Build 14430.20298)

https://www.microsoft.com/de-ch/microsoft-365/roadmap?filters=Outlook&searchterms=70595

[Ard__120]

Will we be able to hook the new isexternalsender MAPI property for purposes such as Rules, Search Folders, Conditional Formatting etc?

[Victor Ivanidze]

Hi @Ard__120, as you know, the "Rules, Search Folders, Conditional Formatting etc" cannot use any MAPI property.

The only way to use  isexternalsender MAPI property is getting it by code in VBA macro or in C#/C++/VBNet add-in.

[GameChanger]

Hello,

I am posting this on October 28, 2021, and it appears this article was last updated on April 2, 2021.  I have been tracking this feature on the Roadmap page since January 2021.  It was showing "in development" until early October 2021, when it changed to "Launched."

I am trying to find out if this feature will work in our hybrid Microsoft 365 environment.   While Microsoft hosts our email environment, we have our AD on-prem as well as an email relay server.   Most of our users use Outlook for Windows (in addition to Outlook in the web and the Outlook app on their phones).  Will this feature work without any issues in a hybrid Microsoft 365 environment?

I think there is a typo for the Outlook build version in the "To Set This Up" section.  It says "Outlook for Windows: available in builds 16.0.13930.10000 and higher" but there is no such version!  We are running Outlook for Windows build 13801.2xxxx (version 2102).   There is no such version of "16.0.1...." on the supported versions page, here:  https://docs.microsoft.com/en-us/officeupdates/update-history-microsoft365-apps-by-date

Is this a mistake or am I missing something?  

Thanks in advance!

David

[cbron]

@GameChanger that is the end portion of the version number. You need to drill in to see the entire version number, which should look something like this.

Microsoft® Outlook® for Microsoft 365 MSO (Version 2109 Build 16.0.14430.20154) 32-bit

All you are seeing is the last part, which in my case would be 14430.20154. 

File | Office Account, then click the button to the left of About Outlook for the full version number.

BTW, it's still not working (at least not as well as Outlook on the Web or Mobile) in the version I am running. This is what you get at the top of an email.

[GameChanger]

@cbron Got it.  Thank you.  I read your previous posts over the past several months (about it not working in Outlook for Windows).  I was thinking the issues were resolved once Microsoft said the feature is "launched", instead of being "in development."

We are running Outlook version 16.0.13801.20840.  Which means we will need to upgrade to 16.0.13930.10000 or higher (per Microsoft).  I understand this.

@KSAgendia @alex_ha19 @dhruv9211 @stukey @shark_it @JrouziesM @billoreilly @Shon Miles @AA1109 @johncrowther @Victor Ivanidze 

But I just want to confirm that this feature (once enabled via PowerShell) works in a hybrid environment.  Also, as was asked by other people before here.... Is there a way to enable this for select users (mailboxes), and not the entire domain?  Without using third party software?  I would like to test it first (and my boss is asking to do this before we push it out to all of our users).

Thanks in advance,

-David

[Andres Bohren]

@GameChanger i have a customer with a Hybrid Configuration. Mails are coming in via OnPrem Exchange Servers. All Mailboxes are in Exchange Online. The Feature works fine in this Configuration.

>Is there a way to enable this for select users (mailboxes), and not the entire domain? 

>I would like to test it first (and my boss is asking to do this before we push it out to all of our users).

Why don't you have a Test Tenant or at Least a Developer Tenant (for free) to test out such things https://blog.icewolf.ch/archive/2021/02/09/m365-developer-tenant-90-day-e5-subscription.aspx

[johnatemps]

Great new feature !

But we can't enable this on our tenant.

Do you have any idea why?

[Andres Bohren]

@johnatemps Do you have the ExchangeOnlineManagement PowerShell Module 2.0.5 installed? Do you own the Role "Exchange Administrator"?

Regards Andres

[johnatemps]

Thank's Andres,

Yes, the ExchangeOnlineMangament Powershell Module is installed.

But i'm just "Company Administrator".

The Role "Exchange Administration" is necessary in addition to "Company Administrator" ?

Regards Jonathan

[johnatemps]

I Tried again with the Exchange Admin rights and i have the same isue.

[ThorstenK2]

sadly it is not very visible compared to the risk. Also there might me other lines in the same scheme that make it easy to overlook.

Also compared to the aggressive Yellow TransportRule-Banner some customers have already implemented, so you can hardly convince them to switch over.

Please make options to configure something like the color or size to make it better visible.

[A-Rex]

@johnatemps 

There is a CMDlet which tells you what role you need to be able to execute a specific other CMDlet.

$Perms = Get-ManagementRole -Cmdlet Set-ExternalInOutlook -CmdletParameters Enabled

Hope this helps you, let me know.

Cheers
Arbër

[ryanBasys]

Can the external sender indicator tags be increased in size? Or customized? 

[Victor Ivanidze]

Hi @ryanBasys,

not natively. You can use this tool: https://www.ivasoft.com/tagexternalflow.shtml  

[Nicola Guarino]

Hi, 

is the feature working on Outlook on Windows?

I believe I am am on a right Office version:

Is there any additional command to run, on the top of Set-ExternalInOutlook?

Thanks in advance for any feedback

Regards,

Nicola

[Ole Thomsen]

I would like an option to color code the tag, red or orange. 

[Victor Ivanidze]

Hi @Ole Thomsen,

unfortunately you can't.  Use a third-party tool instead of native one to get what you want.

[Nicola Guarino]

Hallo,

After our troubles during the weekend, let me share with you the answer I received from O365 support, in reply to my query

1. Can you please confirm if this (External Tag in Outlook) feature is supported also on Outlook for Windows?
1. If yes what are the minimum requirement for office365/Outlook for Windows version/builds?
2. If, no is there a planned release date for this feature to cover also Outlook for Windows?

I hope I can spare some troubles to someone else.

"Quote"

Based on our conversation over the phone on your support request 2949xxxx, the effectiveness of the setexternalinoutlook depends on the version of so many things of which API is one of the most crucial factors on outlook app.

According to this documentation Set-ExternalInOutlook (ExchangePowerShell) | Microsoft Docs windows PC was not added to the device listing in the first paragraph. This shows the feature is still not in full release mode.  Hence, I believe there will be improvement in that aspect soon.

Furthermore, in this document Outlook JavaScript API requirement sets - Office Add-ins | Microsoft Docs it shows the feature is still in developer mode and it shows the diverse versioning from API to server that will be needed plus exact supported add-ins in windows platform that can facilitate this feature.

Here is the resolution, this feature is available but due to the absence of some of the required prerequisites in your windows PC, the installation or configuration might be unsuccessful for now, as more updates are rolled out the issue will be eliminated.

 
Thank you for choosing Microsoft.

"Quote"

I am afraid we will stay with our good old transport rule for a while.

Regards,

Nicola

[Boon88]

Seems that it doesn't work on Outlook 2016 and 2019 desktop clients. Anyone has solution beside using transport rules?

[Nicola Guarino]

Hallo community,

I forgot to share the outcome of my experience.

After a couple of weeks of ranting at Microsoft support, I managed to get a sort of acknowledgment that the documentation on this feature is at best poor.

Set-ExternalInOutlook (ExchangePowerShell) | Microsoft Docs

The feature works great on mobile Outlook apps and on OWA, but does not work yet in Outlook desktop client.

The official reply I got, after my 3rd support request is the following:

Explained to customer that according to Microsoft Tech community and response from our internal team, the feature is expected to become available in Semi Annual Channel starting with Version 2202 which means it for Outlook for windows it is currently unavailable for any other version other than upcoming Semi-Annual Channel starting with version 2202.

But the above is not documented anywhere

Regards,

Nicola