Classic Outlook to New Outlook: Reactions – Use lightweight replies without classic add-ins

You want to reply to an email with a quick thumbs-up or smile in the new Outlook for Windows without installing the classic add-ins you used before. The new Outlook includes a built-in Reactions feature that sends lightweight animated icons through Microsoft 365 servers instead of bulky add-in toolbars. This article explains how Reactions work, what they replace, and how to use them in the new Outlook.

Classic Outlook required third-party add-ins or custom scripts to insert emoji reactions into emails. The new Outlook eliminates that need by integrating Reactions directly into the message compose and reading panes. You can send a Like, Heart, Laugh, Surprise, Sad, or Celebrate reaction with one click.

Reactions appear as inline icons inside the email thread so recipients see them without opening attachments or enabling add-ins. This guide covers the feature overview, step-by-step setup, limitations, and a comparison with classic add-in methods.

How Reactions Work in the New Outlook

Reactions are lightweight inline icons that you send directly from the Reading Pane of any email in the new Outlook. When you click the Reactions button, the icon appears inside the email thread for all recipients who use an email client that supports Reactions. Recipients using classic Outlook, Gmail, or other clients see a plain text fallback: “[Name] reacted with Like” instead of the icon.

The feature uses Microsoft 365 message processing to attach the reaction as a special MIME part that only compatible clients render. No attachment, no add-in, no script runs on the recipient side. The reaction is tied to the specific message and cannot be edited or removed after sending.

Reactions replace the common workaround of inserting emoji images via add-ins like Emoji Keyboard or Insert Emoji. In classic Outlook, users often installed third-party add-ins to paste emoji into the body of an email. Those add-ins created inline images that increased message size and sometimes broke in email clients that blocked external content. Reactions solve both problems by using a single, server-rendered icon.

Prerequisites for Using Reactions

You need the following to send and receive Reactions:

• A Microsoft 365 work or school account. Reactions are not available for personal Outlook.com accounts in the new Outlook.
• The new Outlook for Windows version 1.2023.1 or later. Check your version under File > Office Account > About Outlook.
• Recipients must use an email client that supports Reactions. Supported clients include new Outlook for Windows, Outlook on the web, Outlook for Mac, and Outlook for iOS and Android.
• Exchange Online or Microsoft 365 mailbox. Reactions do not work with on-premises Exchange mailboxes.

Steps to Send a Reaction in the New Outlook

1. Open the email you want to react to
   Double-click the message in your Inbox or select it so it opens in the Reading Pane. The Reactions button is located in the toolbar above the message body.
2. Click the Reactions button
   The button looks like a smiley face with a plus sign. It is the first icon on the left side of the Reading Pane toolbar. A small menu opens showing six reaction options: Like thumbs up, Heart, Laugh, Surprise, Sad, and Celebrate.
3. Select your reaction
   Click one of the six icons. The reaction icon appears immediately below the sender name inside the email thread. A confirmation animation plays briefly. The reaction is sent automatically. You do not need to click Send or close the message.
4. View reactions from others
   When someone sends a reaction to one of your emails, the icon appears below your message in the Reading Pane. Hover your mouse over the reaction to see who sent it. If multiple people react, Outlook groups identical reactions and shows a count.

Turn Reactions On or Off

1. Open Outlook settings
   Click File > Options in the top-left corner. Then select Mail from the left navigation panel.
2. Find the Reactions section
   Scroll down to the Send messages section. Look for the checkbox labeled “Enable Reactions.” It is checked by default.
3. Change the setting
   Uncheck the box to disable Reactions for your account. Click OK to save the change. The Reactions button disappears from the Reading Pane toolbar.

Limitations and Things to Avoid with Reactions

Reactions Do Not Work in Classic Outlook

If you send a reaction from the new Outlook to someone using classic Outlook, the recipient sees a plain text line instead of the icon. The text reads: “[Your Name] reacted with [Reaction Name].” This is not an error. Classic Outlook does not parse the MIME part that contains the reaction icon. The recipient still knows you sent a reaction, but the visual effect is lost.

Reactions Cannot Be Edited or Deleted After Sending

Once you click a reaction icon, it is sent immediately. There is no undo option. If you accidentally send the wrong reaction, send a second reaction to correct it. Both reactions appear in the thread. You cannot remove a reaction from the recipient side. To avoid mistakes, pause before clicking the icon.

Reactions Are Not Available for Encrypted or Sensitivity-Labeled Emails

If you receive an email that is encrypted with Microsoft Purview Message Encryption or has a sensitivity label like Confidential or Highly Confidential, the Reactions button is grayed out. You cannot send a reaction to those messages. The same restriction applies to emails sent from outside your organization that have encryption applied.

Reactions Do Not Work in Shared Mailboxes or Public Folders

If you access a shared mailbox or a public folder in the new Outlook, the Reactions button is not visible. Reactions are available only for messages in your own mailbox. To react to an email in a shared mailbox, forward the message to your personal mailbox first.

Reactions in New Outlook vs Classic Add-Ins: Key Differences

Item	Reactions in New Outlook	Classic Add-Ins for Emoji Replies
Installation required	None built into the app	Manual add-in installation from Office Store or internal source
Recipient compatibility	Works only in Microsoft 365 clients that support Reactions classic Outlook shows plain text fallback	Works in any client that renders inline images but may break if images are blocked
Message size impact	Minimal single MIME part less than 1 KB	Large inline image attachment increases message size by 10-50 KB per emoji
Security restrictions	Blocked on encrypted or sensitivity-labeled emails	May trigger security warnings if add-in requests permissions
Undo or edit after send	Not possible send a second reaction to correct	Not possible unless add-in supports recall which is rare
Availability for shared mailboxes	Not available	Available if add-in is installed for that mailbox

Reactions in the new Outlook are designed for quick, low-friction replies. They replace the need for classic add-ins that were used to insert emoji images into email bodies. The trade-off is limited recipient support and no editing after send. For most internal team communication within Microsoft 365, Reactions work reliably and reduce clutter in the Inbox.

You can now send lightweight replies using the built-in Reactions button in the new Outlook without installing any add-ins. Try using the Heart reaction for positive feedback or the Celebrate reaction for project milestones. If you need to react to an email in a shared mailbox, forward the message to your personal mailbox first. For encrypted messages, use a regular reply instead of a reaction.