“Verifying Microsoft Outlook” Stuck on Mac? 2026 Fixes

“Verifying Microsoft Outlook” is a macOS security check, not a fault in Outlook itself. If the bar stops moving for several minutes, force quit Outlook and the CoreServicesUIAgent process, restart your Mac, then update Outlook. If the message keeps returning, delete only the app and reinstall it from Microsoft or the App Store.

That little window is maddening because it gives you nothing to work with: no error, no button that helps, and an inbox behind it. Below I cover what the check is doing, how long is normal, the fixes in the order I'd try them, and the popular advice that lowers your Mac's security for no good reason.

One thing to do before any of it: get to your mail another way. The last time this window sat on my screen, a client was waiting on an answer, so I replied from a browser and dealt with the Mac afterward. Work and school accounts open at outlook.office365.com, per Microsoft's sign-in page, and personal accounts at outlook.com, per its Hotmail page.

What does “Verifying Microsoft Outlook” mean on a Mac?

The message means macOS is inspecting Microsoft Outlook before letting it run. Apple's security guide says Gatekeeper, the Mac's app-checking system, confirms that software from outside the App Store comes from an identified developer, is notarized (scanned and cleared by Apple) and hasn't been altered. It also says all Mac software is checked for known malicious content the first time it's opened.

A downloaded app that still carries the quarantine flag, a hidden marker macOS puts on downloads, gets the full treatment: a signature check, a malware scan and a notarization check. Part of that work happens online, because the notarization ticket is looked up with Apple during the first run. So a slow bar doesn't mean Outlook has crashed. The window you're looking at comes from a macOS process called CoreServicesUIAgent.

How long should verifying Microsoft Outlook take?

Verifying Microsoft Outlook should take seconds on a recent Mac, and possibly a few minutes on an older one. Microsoft doesn't publish a figure, but there's a useful yardstick. Outlook on the Mac App Store is listed at 1.2 GB, and Eclectic Light's first-run tests on Calibre, another large app, recorded a scan of about 5 seconds on macOS Sequoia 15.7 and about 10 seconds on macOS Tahoe 26.0.

Age of the machine matters too: Eclectic Light found that launch checks mostly hurt on older hardware and are usually negligible on recent Apple silicon. My own cutoff is five minutes. A bar that's still creeping gets left alone, and one that hasn't budged by then gets the fixes below. After a big Office update I open Outlook first and go make coffee, because a new version means new code and a fresh round of checks.

How to clear a stuck “Verifying Microsoft Outlook” window

Clearing a stuck check takes three moves: force quit Outlook, stop CoreServicesUIAgent if the window survives, then restart the Mac. Outlook hasn't opened yet, so there are no drafts in it to lose.

Force quit Microsoft Outlook

1. Press Option-Command-Esc, or choose Force Quit from the Apple menu, as Apple's force quit page describes.
2. Select Microsoft Outlook in the list. If it isn't there, skip to the next section.
3. Click Force Quit.
4. Open Outlook again and watch the bar for a minute.

Stop CoreServicesUIAgent in Activity Monitor

If the window stays on screen, the process drawing it is the one to stop. Apple doesn't document this as a fix for the message, so this one is a community remedy that guides to this error recommend.

1. Open Activity Monitor from Applications > Utilities.
2. Type CoreServicesUIAgent in the search field.
3. Select the process and click the Stop button at the upper left of the window.
4. Choose Force Quit. Apple's Activity Monitor guide warns that this stops a process immediately and can upset anything depending on it, so save your other work first.

Restart your Mac

Open the Apple menu, choose Restart, and clear Reopen windows when logging back in so Outlook doesn't launch straight back into the same hang. If the Mac won't restart, Apple says to hold the power button for up to 10 seconds until it turns off, then press it again. Open Outlook once the Mac has been up for a minute.

How to update Outlook when it won't open

You can update Microsoft Outlook without opening it, because the updater doesn't depend on Outlook running. Try this before a full reinstall: it's quicker, and an old version is a poor place to start troubleshooting. Going by Microsoft's release history, the newest Office for Mac release is 16.114.3, dated October 27, 2026. The route depends on where your copy came from, and Microsoft gives this Terminal command to find out, shown here with Outlook's path. Open Terminal from Applications > Utilities, paste the command and press Return:

mdls -name kMDItemAppStoreReceiptType "/Applications/Microsoft Outlook.app"

A result of (null) means the copy came from Microsoft. Production means Apple's store supplied it.

• App Store copy: open the App Store, select Updates in the sidebar, then click Update next to Microsoft Outlook.
• Microsoft copy: open Word, Excel or another Microsoft 365 app and choose Help > Check for Updates, which opens Microsoft AutoUpdate. Click Update.
• No Help option, or AutoUpdate throws an error: Microsoft says a missing helper file or wrong permissions can cause that, and that installing the latest AutoUpdate should help. The newest package is on its AutoUpdate release page, version 4.85 from September 18, 2026.

While you're there, check macOS too. The App Store listing says Outlook needs macOS 14.0 or later, and an update is under System Settings > General > Software Update.

Why does verifying come back every time you open Outlook?

A repeating check usually means macOS hasn't recorded that Outlook passed. According to Eclectic Light's breakdown of first runs, an app that finishes its first run and gets your approval doesn't go through those checks again, while one where the prompt is declined repeats them on the next launch. Two things are worth checking.

Where the app lives. Outlook belongs in the Applications folder. If a quarantined app runs from the folder it landed in, such as Downloads, macOS runs it from a randomized hidden location each time until you move it. Open Finder, go to Applications, and launch it from there. A copy sitting in Downloads or on a mounted disk image is the one to drag across.

What the quarantine flag says. This Terminal command only reads the flag and changes nothing:

xattr -p com.apple.quarantine "/Applications/Microsoft Outlook.app"

Terminal printing “No such xattr” means there's no flag, so quarantine isn't your problem. A value starting 01c3 is the typical mark of a completed first run. A value starting 0083 is typical of a fresh browser download that hasn't been cleared, and in that case the reinstall below is the clean fix. If you see 01c3 or anything else and the check still repeats, use the same reinstall.

When Outlook only sticks on a company network

An office network can stall the check, because macOS has to reach Apple. Apple's enterprise network page lists api.apple-cloudkit.com for app notarization and ocsp.apple.com for certificate validation, and warns that Apple services fail any connection that uses HTTPS inspection.

When Outlook hung on a company laptop of mine, I tried it on my phone's hotspot before bothering anyone. A quick pass there tells you the network is the likely problem and gives IT something concrete to act on. Do the same with a VPN switched off, if your company allows it. Then send something like this:

Subject: Outlook stuck on "Verifying" on my Mac, office network only

Hi,

Microsoft Outlook hangs on the "Verifying Microsoft Outlook" window on my Mac when I'm on the office network. On my phone hotspot it opens normally.

Could you check that these hosts aren't blocked or going through HTTPS inspection?

api.apple-cloudkit.com (port 443)
ocsp.apple.com (port 80)

Apple lists both here: https://support.apple.com/en-us/101555

Thanks,
[Your name]

Managed Macs have another wrinkle: Apple notes that some security settings may be unavailable when an IT department manages the machine, and Microsoft sends you to your helpdesk if you lack permission to install software. Don't spend your afternoon fighting either one.

Rule out other software with safe mode

Safe mode shows whether software that loads at startup is causing the hang. Security tools and VPN clients would be my first suspects, though Apple doesn't name any. These are Apple's steps:

• Apple silicon: choose Apple menu > Shut Down, then hold the power button until “Loading startup options” appears. Select a volume, hold Shift and click Continue in Safe Mode.
• Intel: turn on or restart the Mac, then hold Shift right away until the login window appears.

Look for “Safe Boot” in the menu bar, then open Outlook. If it passes there, restart normally and remove recent startup software one piece at a time. If every app hangs in both modes, run Disk Utility's First Aid. Apple says to check a startup disk from macOS Recovery, working through its volumes, then the container, then the device.

How to reinstall Outlook on a Mac without losing data

Reinstalling Microsoft Outlook gives macOS a clean copy to check, and deleting only the app leaves your Outlook data in place. The data sits in your Library folder, and Microsoft's uninstall page warns that Outlook data goes when you move those Library folders to the Trash, so it says to back them up first. For this problem you can leave them alone. That's how I handle it: the app goes, the Library stays.

1. Force quit Outlook if it's still open.
2. In Finder, open Applications and move Microsoft Outlook to the Trash.
3. Restart your Mac.
4. Reinstall from the same place you got it. For the App Store, search for Microsoft Outlook. For Microsoft, go to m365.cloud.microsoft/apps, sign in and choose Install apps, as Microsoft's install page describes.
5. Open the new copy from Applications, wait for the check and approve any prompt.
6. If Outlook asks for your password again, our password guide for Mac covers that part.

Only use Microsoft's full uninstall if that doesn't work, and take the backup it asks for. And if Outlook has become more trouble than it's worth, we've compared the alternatives for Mac and set Apple Mail against Outlook.

Which “Verifying Microsoft Outlook” fixes should you skip?

Skip any fix that switches off a macOS protection, because the check isn't the fault. It's the check getting stuck. These turn up often in other guides, and none is worth it for one mail app.

How to stop verifying getting stuck again

• Keep Outlook in the Applications folder and open it from there.
• Turn on Automatically keep Microsoft apps up to date in Microsoft AutoUpdate, or automatic updates in the App Store, so you aren't several versions behind.
• Give Outlook its first launch after an update on a network you trust, and before a meeting rather than during one.
• Keep Outlook on the web bookmarked, so a stuck app never stands between you and your inbox.