Reactions in Outlook: Public usability update September 2023

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This post has been republished via RSS; it originally appeared at: Microsoft Tech Community - Latest Blogs - .

Millions of reactions are used every day 

Outlook users use a myriad of reactions on a daily basis. Thumbs up and hearts decorate congratulatory emails without causing reply-all floods. Sad faces help convey your consolation often when words fail. We see network effects take place especially for wide audience emails – enough people start reacting and everyone else just piles on. We believe we’re witnessing a shift in communication behaviors and preferences within Microsoft and in other companies worldwide. 


We actively learn from feedback as people use reactions. This post will go into more detail about what’s coming up for reactions and what you can do to prepare.


We continue to rollout reactions through the various update channels 

Reactions are available on Outlook on the Web, Outlook for Mac, Outlook for iOS, and Outlook for Android. For classic Outlook for Windows, the rollout is progressing through the Office channels. 


Reactions have already been released to Microsoft 365 Current Channel and Monthly Enterprise Channel users. Semi-Annual Enterprise Channel customers can expect reactions to be available in version 2308, which was newly released to Semi-Annual Enterprise Channel (Preview) customers just a few days ago.


We’re about to release the ability to Disallow Reactions on an email 

We’ve heard from a number of users and admins who tell us that there are times when they’re worried that an email they’re about to send may touch on a difficult topic or for some other reason be better served with reactions turned off. Granular control over which emails get to have reactions had been in our horizon from the start, and we shuffled some priorities to get this released sooner. 


Soon, Outlook users will be able to choose to “Disallow Reactions” on an email they are about to send. The option will be available when users are still drafting their email and cannot be changed after the email is sent. At the client side, the ability for recipients to react to the email will be grayed out and made not clickable. Since Disallow Reactions will roll out to different Outlook clients at different cadences and not all Outlook clients will have the gray-out update immediately, we also have a second layer of protection. When an email has reactions disallowed, attempts to react to it will fail at the server side. 


Exchange Online 

Outlook on the Web and new Outlook for Windows 

Other Outlook clients 

Reactions can be disallowed 

[Released] If the email is tagged with x-ms-reactions: disallow, attempts to react to this email will be rejected and will fail 

[Released] If the email is tagged with x-ms-reactions: disallow, the entry point to react to the email will be grayed out 

Will follow the behavior on Web at a later date 

How can reactions be set to be disallowed? 

[Released] Mail flow rules can be used to stamp the desired SMTP header 

[Rolling out soon] A checkbox to disallow reactions can be checked when composing an email 

Will follow the behavior on Web at a later date 


The ability to use the UI to set Disallow Reactions on an email will be released first to Outlook on the Web and new Outlook for Windows, to be followed later by other Outlook clients. The checkbox can be found in the Options tab when composing a new email. This cannot be changed after the email is sent. 




Additionally, tenant admins can set up Mail flow rules (Transport rules) to automatically stamp the x-ms-reactions: disallow SMTP header when appropriate. Here is an example rule that disallows reactions on emails received from outside the organization: 




Based on this example, you can do lots of other neat combinations, like disallowing reactions when the email is sent by any member of the Legal Team group. 


eDiscovery scenarios can expect better support before the end of 2023 

At this point in time, Reactions data is partially available during eDiscovery. We continue to make progress in this area and plan to deliver additional support before the end of the year. 


Standard eDiscovery 

Premium eDiscovery 

Are reactions in the data when a compliance search is performed? 

Yes, as MAPI properties

Yes, as MAPI properties

Can reactions be seen when the emails are previewed on the Purview website? 

No; not in plans

Not yet – support should be available before the end of the year

Are reactions in the data when emails are exported using Microsoft Purview? 

Only .msg and .pst exports contain reactions data 

Only .msg and .pst exports contain reactions data 

Can you search based on the existence of a certain reaction? 

No; existing search capabilities are unchanged 

No; existing search capabilities are unchanged 


For compliance managers who export .msg and .pst files, the reactions data available currently in MAPI properties can be inspected using any existing tool (our favorite is MFCMAPI). Descriptions of the properties are in the following table, assuming I’m the owner of this mailbox: 

MAPI property name 



Current state of reactions on this message with names of reactors and timestamps 


Timestamp of my current reaction on this message 


My current reaction on this message 


Count of all current reactions on this message 


Every reaction action I’ve ever done on this message (e.g., applying a reaction, removing a reaction) and their timestamps 


Current state of reactions on this message with names of reactors and timestamps similar to MapiReactionsBlob but in a compressed format 

*MapiReactionsBlob is not memory efficientits data is available via ReactionsSummaryand is a candidate for removal in the future. 

**We are currently renaming ReactionsHistory to OwnerReactionHistory to better conform with the pattern where Owner-prefixed properties are related to only the mailbox owner.


We welcome feedback from you! 

We hope you love reactions as much as we do, and with these new and upcoming updates get to customize your and your organization’s usage of the feature to your liking! 

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