Microsoft is installing Outlook-Preview without permission

[German]A somewhat unpleasant observation that some users and administrators are currently reporting. On some systems with Microsoft 365, the preview of the Outlook app is suddenly installed by Microsoft. I have created a short summary of the situation, which I had already taken up in April 2023.

A first observation in April 2023

I had reported in April 2023 in my German blog post  "Testen Sie"-Falle beim neuen Outlook 365-Client; Bug im Outlook für Web about an observation, my German readers made. Microsoft is trying to encourage users to test the "new Outlook Preview" in Office 365/Microsoft 365 via a toggle button.

A German blog reader, who is responsible as an administrator for the systems within a corporation, informed me by email that that he observed the "try the new Outlook" toogle button in Outlook. He wrote, that this change may require a lot of training for the users.

To avoid this issue, administrators can use the advise given within the Microsoft article Release Notes for Beta Channel:

We added a registry key that hides the "Try the new Outlook" toggle:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\General
REG_DWORD "HideNewOutlookToggle"
0 (default) – "Try the new Outlook" toggle, if available in selected update channel, is displayed to users.
1 – "Try the new Outlook" toggle is hidden.

New report on Microsoft Answers

Doing a quick search during writing this blog post, I found the Microsoft Answers forum entry "New" Outlook for Windows UWP App (Preview) Installed Without Permission. A user wrote:

I use Microsoft Office Home and Business 2019 Click-to-Run on my Win 10 v22H2 laptop. After the current Version 2304 / Build 16327.20214 (rel. 25-Apr-2023) update was automatically applied on 02-May-2023 a toggle switch labelled "New Outlook" appeared in the top-right corner of my MS Outlook 2019 interface prompting me to switch to the "new" Microsoft Outlook. At the time I had no idea what the purpose of this switch was but later found more information about this preview of the new Universal Windows Platform (UWP) / Microsoft Store app in the Microsoft support article Getting Started With the New Outlook for Windows and the Microsoft 365 Insider blog at Starting to Support Third-party Accounts in New Outlook for Windows Preview.

I hovered my mouse over that toggle switch to try to find further information about its purpose but I am certain that I never turned that switch on, and the next day I was appalled to discover that this preview of the MS Outlook for Windows UWP app v1.2023.425.600 had been installed on my system without my permission.

In the post, the user complains that Microsoft installed the preview of Outlook or the new Outlook on his system and definitely does not want to be used as a guinea pig for any experiments – especially since he owns a purchased version of Office Home and Business 2019. In the forum post, the user provides more screenshots of this new Outlook entry.

In another post, he states that the "Try the new Outlook" button is now back in the Outlook window after disappearing for a few days in his Microsoft Office Home and Business 2019.

Also in the tech community there is this user entry from April 2023 where someone describes problems with "Try Now public preview of Outlook 365" and had to repair the app.

Report on patchlist.org

However, I came across the topic again on Sunday while looking into my mailbox. I received a notification about a new entryg MS 365 & Outlook issues at patchlist.org . An administrator wrots on May 11, 2023:

I'm seeing issues on 4 devices so far where, after Tuesday, the Windows Mail app is now rebranded as "Outlook Pre" (I assume it stands for preview) and replaced the Outlook 365 icons and shortcuts. Opening it (Outlook Pre) causes Outlook from MS 365 to be disabled.

Using the control panel to try to repair MS 365 (to get Outlook back) causes MS 365 to be removed COMPLETELY. Reinstalling MS 365 from office.com is the only way to get it all working again.

We're in a very rural area so this is a painful process since the download is just a stub. Many of our clients still only have 5 mbps connections.

So again, the new Outlook app was replaced without being asked. And the only way to get to the old Outlook is to reinstall from the office.com website. Particularly frustrating: These are probably different customers who live in US areas with poor Internet connections. The affected person then created the following batch program to prevent the switch to the new Outlook.

'// ========================================================
' Ensure Outlook stays Outlook
'// ========================================================
FOR /D %%u IN ("%SystemDrive%\Users\*") DO (
DEL
"%%u\AppData\Local\Packages\microsoft.windowscommunicationsapps_8wekyb3d
8bbwe\LocalState\Migration\settings.json" 1>NUL 2>NUL
)
REG.exe ADD
"HKLM\Software\Microsoft\Office.0\Outlook\Options\General" /v
HideNewOutlookToggle /t reg_dword /d 1 /f 1>NUL 2>NUL
REG.exe ADD "HKLM\Software\Microsoft\Office.0\Outlook\Preferences" /v
UseNewOutlook /t reg_dword /d 0 /f 1>NUL 2>NUL
FOR /F "usebackq tokens=* delims=" %%k IN (`REG.exe QUERY HKU ^| FINDSTR
"\\" ^| FINDSTR -v "_Classes"`) DO (
REG.exe ADD
"%%k\Software\Microsoft\Office.0\Outlook\Options\General" /v
HideNewOutlookToggle /t reg_dword /d 1 /f 1>NUL 2>NUL
REG.exe ADD
"%%k\Software\Microsoft\Office.0\Outlook\Preferences" /v
UseNewOutlook /t reg_dword /d 0 /f 1>NUL 2>NUL
)
'// ========================================================

Have any of you been affected by this foisted new Outlook (Preview) the last few days?