Start regedit.exe
Go to HKEY_CURRENT_USER\SOFTWARE\Microsoft\office\16.0\outlook\autodiscover
Create new DWORD: ExcludeExplicitO365Endpoint with Value = 1
Start regedit.exe
Go to HKEY_CURRENT_USER\SOFTWARE\Microsoft\office\16.0\outlook\autodiscover
Create new DWORD: ExcludeExplicitO365Endpoint with Value = 1