Outlook 2016 / 2021 Pro keeps asking for Password E1 Licenses

VFS@BID 0 Reputation points

Starting yesterday, desktop versions of Office Professional 2016 and 2021 keep prompting for password. The Windows Security window will not go away even with checking to remember password. A call to MS support said it was because the user was not the person Office was registered to due to modern authentication. Regedit to force Outlook to use MO did not work. This does not make sense. A fully licensed copy of Office installed on a single workstation is able to be used by multiple domain users. We have 3 shifts 7 days a week with multiple users sharing a workstation. Email box is fully functional on webmail. While email is not down, this is very inconvenient for users who access multiple email boxes.

Microsoft Exchange Online
A suite of Microsoft productivity software that supports common business tasks, including word processing, email, presentations, and data management and analysis.
243 questions
Windows 10 Security
Windows 10 Security
Windows 10: A Microsoft operating system that runs on personal computers and tablets.Security: The precautions taken to guard against crime, attack, sabotage, espionage, or another threat.
2,227 questions
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  1. Amit Singh 3,416 Reputation points

    You can disable this check for an on-premise Exchange Server. Go to the registry key HKEY_CURRENT_USER\Software \Microsoft\Office\16.0\Outlook\AutoDiscover and create a new DWORD parameter named ExcludeExplicitO365Endpoint and value 1. Restart Outlook.e

    You can make changes to the registry with the following command:

    reg add HKEY_CURRENT_USER\Software\Microsoft\Office\x.0\Outlook\AutoDiscover /t REG_DWORD /v ExcludeExplicitO365Endpoint /d 1

    Or, using the PowerShell cmdlet Set-ItemProperty:

    Set-ItemProperty -Path "HKCU:\Software\Microsoft\Office\16.0\Outlook\AutoDiscover" -Name 'ExcludeExplicitO365Endpoint' -Value 1 -Type DWORD –Force

  2. Jame Xu-MSFT 3,881 Reputation points Microsoft Vendor

    Hi @VFS@BID ,

    This issue can occur if the Logon network security setting on the Security tab of the Microsoft Exchange dialog box is set to a value other than Anonymous Authentication.

    Noting that you have contacted MS support, and considering the impact of modern authentication, you could refer to this: Outlook continually prompts for your password when you try to connect to Microsoft 365

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment". 

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