version 16005.14326.21740.0 I have used every tip i have found online so far none of them work. I have also created registry keys and installed the dword as specified on all the tips online. none of them work. nagging popup still exists...
Hi Igor Berezin:
Are you using Windows Mail or Microsoft Outlook as your email client? If I go to Settings | Apps | Apps and Features I can see that 16005.14326.21740.0 is the current version number of the Mail and Calendar app that is built into my Win 10 OS, not the version number of Microsoft Outlook that comes with a paid subscription of a Microsoft Office suite (currently Version 2310 / Build 16924.20150) like Microsoft 365 or Microsoft Office 2016 / 2019 / 2021 Click-to-Run.

The HideNewOutlookToggle registry key edit Diane Poremsky suggested <here> on 12-Feb-2023 will only hide the "Try the New Outlook" toggle switch in Microsoft Outlook, not in Windows Mail.
The July 2023 BleepingComputer article Microsoft force-migrating Windows Mail & Calendar apps to Outlook app in August states that the Mail and Calendar app is being retired in 2024 and will no longer be supported or available for download, so at some point in the coming months users who are still using the built-in Windows Mail app as their email client will be forced to switch to the “new” Outlook for Windows progressive web app (PWA).
If users don’t like the “new” Outlook for Windows PWA when they are finally forced to abandon their Mail and Calendar app they might consider switching to a free third-party email client like Thunderbird or eM Client.
Dell Inspiron 5584 * 64-bit Win 10 Pro v22H2 build 19045.3693 * Firefox v120.0.0 * Microsoft Defender v4.18.23100.2009-1.1.23100.2009 * Malwarebytes Premium v4.6.6.294-1.0.2189 * Macrium Reflect Free v8.0.7690 * Microsoft Office Home and Business 2019 Version 2310 / Build 16924.20150 Click-to-Run