If you use Microsoft 365 Copilot to summarize email threads in Outlook, you may have noticed differences between the classic version and the new Outlook for Windows. The new Outlook uses a different codebase and a redesigned interface, which affects how Copilot features appear and behave. This article explains the specific changes to the Copilot email summary feature, including where to find it, how it works, and what commands are now available.
Key Takeaways: Copilot Email Summary Changes in New Outlook
- Home > Copilot > Summarize by Copilot: In new Outlook, the summary button moved from the Reading Pane toolbar to the Home ribbon under the Copilot group.
- Inline summary panel vs pop-out pane: Classic Outlook opened a side pane; new Outlook displays the summary directly in the Reading Pane below the email header.
- No automatic trigger on long threads: New Outlook does not auto-summarize threads with more than 10 messages. You must click the button manually.
How Copilot Email Summary Worked in Classic Outlook
In classic Outlook for Windows (the traditional .pst-based client), Copilot email summary appeared as a button in the Reading Pane toolbar when you selected a message in a thread. Clicking the button opened a side pane on the right side of the Outlook window. The pane displayed a bulleted list of key points, action items, and decisions extracted from the selected thread. The summary was generated from the entire thread, including inline replies and attachments when supported. Classic Outlook also offered a one-click “Summarize by Copilot” option in the context menu when right-clicking a thread in the message list.
Where Copilot Email Summary Appears in New Outlook
New Outlook for Windows uses a web-based architecture and a simplified ribbon. The Copilot email summary feature is now located in the Home tab of the ribbon, inside a group labeled Copilot. The button is labeled Summarize by Copilot. You must first select a thread in the message list or open a message in the Reading Pane. The summary does not appear automatically. After you click the button, the summary renders inline, directly below the email header in the Reading Pane, replacing the preview of the email body. There is no separate side pane. To dismiss the summary, click the Close button in the summary header or select a different message.
Keyboard Shortcut Change
In classic Outlook, there was no default keyboard shortcut for Copilot summary. In new Outlook, you can press Alt + H to open the Home tab, then press Y followed by S to trigger the summary. This keystroke sequence may vary if your ribbon is customized. The Alt key access keys are visible when you press and release Alt.
Summary Content and Format Changes
The content structure of the summary itself has changed. In classic Outlook, the summary appeared as a bulleted list with bold headings for each category: Key Points, Action Items, and Decisions. In new Outlook, the summary is a single block of plain text divided by line breaks. Key points are prefixed with a dash, action items with a checkbox symbol, and decisions with a right arrow. The formatting is less structured, but the information density is similar. The new Outlook summary also includes a timestamp indicating when the summary was generated.
Prerequisites for Copilot Email Summary in New Outlook
To use Copilot email summary in new Outlook, you must meet these conditions:
- A Microsoft 365 Copilot license assigned to your user account
- New Outlook for Windows version 1.2024.100.100 or later
- An active internet connection
- The thread must contain at least two messages (classic Outlook required at least three)
- All messages in the thread must be in the same mailbox (no cross-mailbox threading)
Steps to Use Copilot Email Summary in New Outlook
- Select a thread in the message list
Click any message in a conversation thread. The thread must contain at least two messages. Single messages cannot be summarized. - Open the Home tab on the ribbon
Click the Home tab at the top of the Outlook window. The ribbon displays the Copilot group. - Click Summarize by Copilot
In the Copilot group, click the Summarize by Copilot button. A loading indicator appears in the Reading Pane. - Read the summary inline
The summary appears below the email header. It contains key points, action items, and decisions extracted from the thread. - Close the summary
Click the Close button in the upper-right corner of the summary area. The original email body reappears.
If Copilot Email Summary Does Not Appear in New Outlook
Copilot button is grayed out or missing
The Copilot button appears gray if your account does not have a Copilot license, if the selected item is not a thread, or if you are offline. Verify your license assignment in the Microsoft 365 admin center. Confirm that you selected a thread with at least two messages. Check your internet connection.
Summary shows an error message
If the summary fails to generate, close the summary area and wait 30 seconds. Then click Summarize by Copilot again. If the error persists, restart new Outlook. The issue may be caused by a temporary service outage on the Copilot server side.
Summary is blank or incomplete
A blank summary usually indicates that the thread contains only very short replies or inline images without text. Copilot requires a minimum amount of text to generate a summary. Add more descriptive text to the thread and try again.
Copilot Email Summary: Classic Outlook vs New Outlook
| Item | Classic Outlook | New Outlook |
|---|---|---|
| Button location | Reading Pane toolbar | Home ribbon > Copilot group |
| Summary display | Side pane on the right | Inline below email header |
| Minimum thread size | 3 messages | 2 messages |
| Auto-summarize on long threads | Yes, for threads over 10 messages | No, must click manually |
| Summary format | Bulleted list with bold headings | Plain text with dash and checkbox symbols |
| Keyboard shortcut | None | Alt + H, Y, S |
| Context menu option | Yes, right-click thread | Not available |
The Copilot email summary feature in new Outlook is functionally equivalent to classic Outlook but uses a different interface and interaction model. The inline display saves screen space compared to the side pane. However, the removal of the context menu option and the automatic trigger on long threads means you must actively initiate the summary each time. If you rely on automatic summaries for long threads, you can add a Quick Step in new Outlook that runs the Summarize by Copilot command with a single click. Create a new Quick Step from Home > Quick Steps > Create New, select Copilot Summarize as the action, and assign a shortcut key.