One of the most practical uses of Microsoft Copilot in Outlook is its ability to summarize long email threads. Instead of scrolling through dozens of replies, you can ask Copilot for a quick summary. But when Copilot fails to summarize email threads, you are back to reading everything manually.
Here is what might be going wrong and how to fix it.
Why Copilot Cannot Summarize Your Emails
License requirements come first. Copilot in Outlook requires a Microsoft 365 Copilot license, which is an add-on to your standard subscription. Without this specific license, the LISBOA77 summarization feature will not be available.
The length or structure of the email thread can cause problems. If the thread is extremely long, contains embedded images instead of text, or includes heavily formatted HTML content, Copilot may struggle to parse and summarize it.
Copilot works best in the new Outlook experience and the Outlook desktop app with the latest updates. If you are using the classic Outlook interface or an older version of the application, summarization features may not be fully supported.
Privacy and compliance settings in your organization can restrict Copilot’s ability to read email content. Some organizations disable AI features for certain mailboxes or sensitivity labels.
Quick Steps to Get Summaries Working
Confirm that your account has a Copilot license. Check with your IT department or look at your Microsoft 365 subscription details to verify.
Make sure you are using the latest version of Outlook. Update the desktop app through File, then Account, then Update Options. If you are using Outlook on the web, try the new Outlook toggle to switch to the updated interface.
Try summarizing a different email thread. If Copilot works on other threads but not on a specific one, the issue may be with that particular email’s content or format.
Check that the email thread contains actual text content rather than images or heavily encoded HTML. Copilot needs readable text to generate summaries.
If the Problem Persists
Sign out of your Microsoft account in Outlook and sign back in. This refreshes your authentication tokens and license validation.
If you are in a managed organization, ask your IT team whether Copilot features are enabled for your mailbox. They can check the admin settings and enable summarization if it has been restricted.
Disable and re-enable the Copilot add-in in Outlook. Go to File, Options, Add-ins, and manage the Copilot add-in. Removing and re-adding it can resolve loading issues.
Try using Copilot summarization in Outlook on the web as an alternative. The web version sometimes handles features differently from the desktop app.
Data Security Considerations
When Copilot summarizes an email thread, it processes the content through Microsoft’s AI services. If your emails contain sensitive or confidential information, be aware that this data is being analyzed by the AI system.
Organizations with strict data handling requirements should review Microsoft’s Copilot data processing policies before enabling summarization across the company.
Summary
Copilot not summarizing email threads in Outlook is typically a licensing, version, or organizational policy issue. Verifying your Copilot license, updating Outlook, and checking with your IT department are the most effective steps to restore this feature.
