outlook default

Question

outlook default

Jimmy Bland 0

i've tried several times to make outlook my default email client but keep getting this pop up every time i log on (see screenshot attachment) Screenshot 2025-10-11 161542

JImmy

Gabe Bratton 836 Reputation points Microsoft Employee Moderator

2025-10-13T21:37:32.8+00:00

Do you have iCloud installed? If so, try launching iCloud and then click "Verify your Apple Account..."

Alternately, open Outlook then click File, Options, Add-ins, Go, and disable the iCloud add-in. Use this option if you have the add-in but are not using iCloud. If iCloud is not your issue but you have other third party add-ins, test disabling those to check if it helps.
Jimmy Bland 0 Reputation points

2025-10-13T22:54:36.07+00:00

thank you Gabe, yes i verified as suggested. Also, I removed all addins from the options. still no joy. ive uninstalled 365 and reinstalled several times but the damn thing keeps popping up when i start my laptop
Gabe Bratton 836 Reputation points Microsoft Employee Moderator

2025-10-14T13:58:50.78+00:00

Just to double check, but do you have iCloud installed? If so, try disabling it in Windows start up. Click the Windows Start button, type Startup, click Startup Apps. Note which iCloud options are enabled and then disable them. Then restart the computer and see if the issue reoccurs.

If this mitigates it and you want iCloud, you will need to reconfigure it for the Outlook profile. I can share more steps if that is the issue.

There is another Outlook called new Outlook. It might also be an option for you. With new Outlook you can add your icloud.com email address directly and it natively syncs contacts and calendar. The Outlook Team is currently rolling out native OAuth support. If you add your account, it might already have this support so you can add it with your normal login and password. If you try it and that does not work you can get an App Password from the Apple account settings, https://account.apple.com/account/manage. Use this instead of the regular password.

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Your answer

Gabe Bratton 836 Reputation points Microsoft Employee Moderator

2025-10-13T21:37:32.8+00:00

Do you have iCloud installed? If so, try launching iCloud and then click "Verify your Apple Account..."

Alternately, open Outlook then click File, Options, Add-ins, Go, and disable the iCloud add-in. Use this option if you have the add-in but are not using iCloud. If iCloud is not your issue but you have other third party add-ins, test disabling those to check if it helps.
Jimmy Bland 0 Reputation points

2025-10-13T22:54:36.07+00:00

thank you Gabe, yes i verified as suggested. Also, I removed all addins from the options. still no joy. ive uninstalled 365 and reinstalled several times but the damn thing keeps popping up when i start my laptop
Gabe Bratton 836 Reputation points Microsoft Employee Moderator

2025-10-14T13:58:50.78+00:00

Just to double check, but do you have iCloud installed? If so, try disabling it in Windows start up. Click the Windows Start button, type Startup, click Startup Apps. Note which iCloud options are enabled and then disable them. Then restart the computer and see if the issue reoccurs.

If this mitigates it and you want iCloud, you will need to reconfigure it for the Outlook profile. I can share more steps if that is the issue.

There is another Outlook called new Outlook. It might also be an option for you. With new Outlook you can add your icloud.com email address directly and it natively syncs contacts and calendar. The Outlook Team is currently rolling out native OAuth support. If you add your account, it might already have this support so you can add it with your normal login and password. If you try it and that does not work you can get an App Password from the Apple account settings, https://account.apple.com/account/manage. Use this instead of the regular password.

Answer 1

Emmanuel Santana 39,620 Independent Advisor

Hello. Which version of Outlook are you running (for example, Microsoft 365 Click-to-Run, Office 2021, or an older standalone release)?

Can you check the exact build number under File > Office Account > About Outlook?

Jimmy Bland 0 Reputation points

2025-10-11T07:25:14.1066667+00:00

Hi Emmanuel

this is the build number

(Version 2509 Build 16.0.19231.20138) 64-bit

Jimmy
Emmanuel Santana 39,620 Reputation points Independent Advisor

2025-10-11T07:30:16.68+00:00
Thanks for confirming. Try these steps:

Press Windows + R, type regedit, and press Enter.

Navigate to this key: HKEY_LOCAL_MACHINE\SOFTWARE\Clients\Mail\Microsoft Outlook

In the right pane, double-click MSMapiApps. If you see a value named Version that’s blank, delete it.

Close Registry Editor.

Open an elevated Command Prompt and run:
"C:\Program Files\Microsoft Office\root\Office16\OUTLOOK.EXE" /regserver

Restart Windows.

If the message still appears, run a Quick Repair of Office via: Settings > Apps > Installed Apps > Microsoft 365 > Modify > Quick Repair.

You can check more info on that error in this official Microsoft guide:

https://learn.microsoft.com/en-us/office/troubleshoot/office-suite-issues/no-default-mail-client-error
Jimmy Bland 0 Reputation points

2025-10-11T07:50:22.2466667+00:00

there is no MSMapiApps. visible???Screenshot 2025-10-11 174837.png
Emmanuel Santana 39,620 Reputation points Independent Advisor

2025-10-11T08:02:29.1266667+00:00
That’s fine, it means Outlook hasn’t created any custom MAPI mappings yet, so there’s nothing to delete. In that case, move on to the next step:

Close Outlook completely.

Open Command Prompt as Administrator.

Run this exact command:
"C:\Program Files\Microsoft Office\root\Office16\OUTLOOK.EXE" /regserver

Wait a few seconds, then restart Windows and open Outlook again.
Jimmy Bland 0 Reputation points

2025-10-11T08:23:49.09+00:00

Screenshot 2025-10-11 182032.png

it opens with C : \ Windows\System32?????
Emmanuel Santana 39,620 Reputation points Independent Advisor

2025-10-11T08:46:15.87+00:00

That’s expected. You’re just launching the command from the System32 working directory, no problem there.

Close Outlook completely (check Task Manager and end any “Outlook.exe” or “OfficeClickToRun.exe” processes). Then run this command instead:

"C:\Program Files\Microsoft Office\root\Office16\OUTLOOK.EXE" /resetnavpane
Jimmy Bland 0 Reputation points

2025-10-11T09:07:50.3166667+00:00

Screenshot 2025-10-11 190647.png
Emmanuel Santana 39,620 Reputation points Independent Advisor

2025-10-11T09:15:49.1566667+00:00
Thanks for the update. You’re missing the opening quote at the start of the path. Run it exactly like this:

"C:\Program Files\Microsoft Office\root\Office16\OUTLOOK.EXE" /resetnavpane

The quote must begin before C: and end after .EXE. There should be a space after the closing quote, before /resetnavpane.

That will execute correctly.
Jimmy Bland 0 Reputation points

2025-10-11T09:20:18.2133333+00:00

oh sorry yes that worked. So, it opened Outlook..... now what?
Jimmy Bland 0 Reputation points

2025-10-11T10:48:54.37+00:00

Sorry but outlook always opened but the pop up keeps appearing whenever I log in, so annoying
Emmanuel Santana 39,620 Reputation points Independent Advisor

2025-10-12T08:04:09.84+00:00
Thanks for the update. Sorry late reply. Let’s verify if Windows is still losing Outlook’s registration during startup.

Press Windows + R, type regedit, and press Enter.

Go to: HKEY_LOCAL_MACHINE\SOFTWARE\Clients\Mail

In the right panel, check the (Default) value. It must say Microsoft Outlook exactly. If not, double-click it and type that name.

Still in that key, confirm there’s an entry named MSIComponentID. If it’s missing, open Settings > Apps > Installed Apps > Microsoft 365 > Modify > Quick Repair , this restores it automatically.

Then check: HKEY_LOCAL_MACHINE\SOFTWARE\RegisteredApplications

Find Outlook.Application. If it’s not listed, right-click, choose New > String Value, and set the name to Outlook.Application.

Double-click it and set its value to: Software\Clients\Mail\Microsoft Outlook\Capabilities

Close the Registry Editor and restart Windows.

Try checking these reference articles if there's anything we are missing: https://learn.microsoft.com/en-us/office/troubleshoot/office-suite-issues/no-default-mail-client-error https://learn.microsoft.com/en-us/previous-versions/troubleshoot/outlook/no-default-mail-client-error-when-msicomponentid-is-wrong

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