The Outlook application is running very slowly and is not displaying emails for today

For Outlook on Apple devices, the supported checks from the available guidance are:

1. Check whether Outlook is still busy in the background. In Outlook for Mac, look at the bottom of the Outlook window for status messages such as Updating mailbox, Downloading, or Syncing. If those appear, wait 2 to 3 minutes and test again.
2. Force quit Outlook and restart it.
   • Press Option + Command + Esc
   • Select Microsoft Outlook
   • Select Force Quit
   • Reopen Outlook for Mac
3. Make sure Outlook and macOS are up to date. Older Outlook for Mac or macOS versions can contain issues already corrected in updates.
4. Check whether an add-in is causing the slowdown or freeze.
   • Open Outlook for Mac
   • Select Tools > Get Add-ins
   • Open My add-ins
   • Temporarily disable or remove recently installed third-party add-ins
   • Quit and reopen Outlook
   • Test whether mail loads normally
5. Test with another macOS user account.
   • In Settings, search for Users and Groups and add a user
   • Sign in to the new macOS account
   • Open Outlook and add the affected email account If Outlook works there, the issue is likely tied to the original macOS user profile.
6. If Outlook is slow when opening messages or sending mail, check whether there is a Microsoft 365 service issue. For Microsoft 365 business accounts, an Exchange Online service issue can cause Outlook to respond slowly or delay mail activity. An administrator can sign in to the Microsoft 365 portal and check service health.
7. If the mailbox is very large, Outlook for Mac can slow down while syncing. Supported cleanup steps include:
   • Empty the Trash folder
   • Move older messages to On My Computer folders
   • Export older items to an Outlook for Mac archive file
8. If folders are slow to open, change the sort field. Sorting by less common fields can be slower. For mail, faster sort fields are Date Received and Subject.
9. Turn off Outlook logging if it was enabled. Logging can slow Outlook.
   • Select Window > Sync Errors
   • Click the Action button
   • Clear Turn on logging for troubleshooting
   • Restart Outlook
10. Check whether Legacy Outlook is still enabled. Legacy Outlook for Mac uses EWS in Exchange Online, and Microsoft recommends turning off the Legacy Outlook switch to avoid disruption.

If the issue started suddenly today across multiple Apple devices, the fastest supported path is to first check for background sync activity, restart Outlook, verify updates, disable add-ins, and have the Microsoft 365 administrator check service health for Exchange Online.

• Outlook for Mac not responding, hangs, freezes, or stops working | Microsoft Support
• Outlook for Mac not responding, hangs, freezes, or stops working | Microsoft Support
• Outlook performance is slow in the Microsoft 365 environment
• Outlook is running slow | Microsoft Support