How to Enable Outlook Reactions in Reply Chains Across Mixed Clients

Outlook reactions let you respond to an email with a thumbs up, heart, laugh, or other emoji without sending a full reply. This feature works inside the same Microsoft 365 tenant but can break when recipients use older Outlook clients or third-party email apps. The reactions may appear as inline text, fail to render, or cause confusion in reply chains. This article explains how to configure Outlook so reactions display correctly for all recipients regardless of their email client.

How Outlook Reactions Work and Why Mixed Clients Cause Problems

Outlook reactions were introduced in 2021 for Microsoft 365 subscribers. When you react to an email, Outlook sends a lightweight notification to the sender. In reply chains, Outlook can render the reaction as a visual icon or as inline text depending on the recipient’s client. The technical challenge is that reactions rely on modern Exchange Online message properties that older Outlook versions and non-Microsoft clients do not understand.

When a recipient opens the reply chain in Outlook 2019, Outlook 2016, or a third-party client such as Gmail or Apple Mail, the reaction may appear as a plain text string like “John Doe reacted with thumbs up to your message.” This inline text breaks the flow of the conversation and can confuse users who expect a visual icon. In some cases, the reaction text is duplicated every time the email is forwarded or replied to, creating clutter.

Microsoft addressed this with a server-side change announced in message center notification MC633016. The change causes Exchange Online to render reactions as inline text by default when a recipient is not using a compatible Outlook client. This setting can be overridden by administrators using PowerShell or by individual users adjusting their own mailbox settings.

Prerequisites for Using Outlook Reactions

You need a Microsoft 365 subscription that includes Exchange Online. Reactions are not available in on-premises Exchange Server or standalone Outlook without a Microsoft 365 license. Both the sender and the recipient must have mailboxes hosted in Exchange Online, though the recipient can use any email client to read the reaction text. To send reactions, you must use Outlook on the web, Outlook for Windows version 2202 or later, or Outlook for Mac version 16.58 or later.

Steps to Enable Reactions and Ensure Compatibility in Reply Chains

The configuration involves two parts: enabling reactions on your own mailbox and adjusting how reactions are rendered in reply chains for mixed clients. Follow the steps below in order.

1. Enable Reactions on Your Mailbox Using Outlook on the Web
   Open Outlook on the web in a browser. Click the gear icon in the top-right corner and select View all Outlook settings. Go to Mail > Reactions. Under “Reactions,” toggle the switch to On. This allows you to send reactions to emails. The change takes effect immediately.
2. Check Your Outlook Client Version
   In Outlook for Windows, go to File > Office Account > About Outlook. Confirm the version is 2202 or later. In Outlook for Mac, open the Outlook menu and select About Outlook. Version 16.58 or later is required. If your version is older, run Microsoft 365 updates from File > Office Account > Update Options > Update Now.
3. Adjust Reaction Rendering in Reply Chains via PowerShell (Admin)
   If you are an Exchange Online administrator, use the Set-MailboxMessageConfiguration cmdlet to control reaction rendering for all users. Connect to Exchange Online PowerShell. Run the following command for each mailbox or use a filter to target all users:
   Set-MailboxMessageConfiguration -Identity user@domain.com -ReactOnMessage $true -ReactOnMessageRendering $false
   The parameter -ReactOnMessage allows reactions to be sent. The parameter -ReactOnMessageRendering set to $false forces Exchange Online to render reactions as inline text for all recipients, preventing broken formatting in mixed-client reply chains. To apply to all mailboxes, use:
   Get-Mailbox -ResultSize Unlimited | Set-MailboxMessageConfiguration -ReactOnMessage $true -ReactOnMessageRendering $false
4. Verify the Change for a Specific User
   Run Get-MailboxMessageConfiguration -Identity user@domain.com | Format-List ReactOnMessage, ReactOnMessageRendering to confirm the settings. ReactOnMessage should show True and ReactOnMessageRendering should show False.
5. Test a Reaction in a Reply Chain
   Send an email to a colleague who uses a different client, such as Outlook 2019 or Gmail. Open the sent message in the recipient’s client and add a reaction. The recipient should see inline text like “You reacted with laugh to this message” instead of a broken icon. Reply to the same email and confirm the reaction text does not duplicate or cause formatting errors.

Common Issues with Outlook Reactions in Mixed Environments

Reactions appear as broken image placeholders in the reply chain

This occurs when the recipient’s email client cannot interpret the modern reaction icon format. The fix is to set ReactOnMessageRendering to $false as shown in step 3. This forces inline text rendering, which all clients can display. If you cannot run PowerShell, ask your Exchange Online administrator to apply the change.

Reaction text duplicates every time the email is forwarded

When a reaction is added to an email and the email is then forwarded, the reaction text is included in the forwarded message body. This is by design. To prevent duplication, avoid adding reactions to emails that will be forwarded to external recipients. If duplication already exists, the recipient can delete the reaction text manually before forwarding. There is no server-side setting to strip reaction text from forwarded messages.

Reactions are not available in the Outlook mobile app

Outlook for iOS and Android do not support sending reactions. You can view reactions that were sent from a desktop client, but you cannot add a reaction from the mobile app. To send a reaction, use Outlook on the web or a desktop client that meets the version requirements. Microsoft has not announced a timeline for mobile reaction support.

Outlook Reactions vs Inline Text Rendering: Key Differences

Item	Visual Icon Rendering	Inline Text Rendering
Description	Reaction appears as a colored emoji icon next to the message header	Reaction appears as plain text inside the email body
Supported clients	Outlook for Windows 2202+, Outlook for Mac 16.58+, Outlook on the web	All email clients including Outlook 2019, Gmail, Apple Mail, Thunderbird
Exchange Online setting	ReactOnMessageRendering = $true	ReactOnMessageRendering = $false
Best for	Homogeneous Microsoft 365 environment	Mixed-client organizations with external recipients
Risk in reply chains	Broken image or missing icon for incompatible clients	Reaction text may clutter forwarded messages

Conclusion

You can now enable Outlook reactions and control how they appear in reply chains when recipients use different email clients. The key setting is the ReactOnMessageRendering parameter in Exchange Online PowerShell, which forces inline text rendering for maximum compatibility. Test reactions with a colleague who uses an older Outlook version or a third-party client to confirm the formatting works. As a next step, review your organization’s email client diversity and apply the inline rendering setting to all mailboxes if more than 10 percent of recipients use non-Microsoft clients.