Office for Mac Issues

How to Fix Outlook Window Resizing After Microsoft 365 Mac Update

Phi Hung Vo Sep 29, 2026 868 views

Question details

The user needs to stop the Outlook application from automatically and repeatedly resizing its window after installing an update.

How to Fix Outlook Window Resizing After a Microsoft 365 Mac Update

Product: Microsoft Outlook for Mac
Device & OS: macOS
Scenario: Launching and using Outlook on a Mac immediately following a recent Microsoft 365 software update.
Observed behavior: The Outlook application window resizes itself unexpectedly and repeatedly, likely due to corrupted preference files or an incomplete update.

Before you start

Ensure you completely quit the Outlook application and save any draft emails before attempting to modify system preference files.

Solution 1Recommended

Reset Outlook for Mac Preferences

Removing corrupted preference files forces Outlook to generate new, healthy configuration files, which is the most effective way to resolve UI and window sizing glitches.

System updates can sometimes corrupt the existing .plist (property list) files that store your application's layout and window size settings. Resetting this file does not delete your emails.

Quit the Outlook application

Right-click the Outlook icon in your Mac dock and select 'Quit', or press Cmd + Q while Outlook is open.

Access the hidden Library folder

Open Finder. Click 'Go' in the top menu bar, hold down the Option (Alt) key on your keyboard to reveal the 'Library' option, and click it.

Locate and remove the preference file

Navigate to the 'Preferences' folder. Find the file named 'com.microsoft.Outlook.plist' and drag it to the Trash.

Restart your Mac and test

Restart your computer, then reopen Outlook. The window should now remain stable at your preferred size.

Safe Process: Your emails, contacts, and calendar events are stored securely in a different database folder. Deleting the .plist file only resets interface settings.

Solution 2

Check for Additional Microsoft 365 Updates

Applying a follow-up patch can fix known display bugs introduced in a previous version.

Solution 3

Reinstall Microsoft 365 for Mac

A clean installation resolves deep application conflicts or broken files caused by an incomplete update process.

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Frequently Asked Questions

Why does my Outlook window keep resizing itself after an update?

This usually happens because the update process corrupted the application's preference file (com.microsoft.Outlook.plist), which dictates the window layout. It can also be caused by temporary conflicts with macOS display scaling features.

Will deleting the com.microsoft.Outlook.plist file delete my emails?

No. The .plist file only contains user interface preferences, such as window size, pane layouts, and toolbar settings. Your emails, contacts, and calendar data are stored in a separate, secure database on your Mac.

How do I find the Library folder if it is hidden on my Mac?

Apple hides the user Library folder by default to prevent accidental system changes. To access it, click on the desktop to activate Finder, click 'Go' in the top menu bar, and hold down the Option (Alt) key. The 'Library' option will appear in the dropdown menu.

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