When connection Outlook 2016 to hosted Exchange it can take an extended period of time (up to thirty minutes)
To reduce this, you can add a registry key to your PC that will speed this process up. * Note: you will require administration rights to be able to perform this action.
You will need to open a Powershell prompt from the Start menu. Open the Start menu and type "Powershell". In the list of applications, locate the one called "Windows Powershell" and right-click on it. Then click "Run as Administrator".
A blue command window should appear. Paste in the following lines:
New-Item -Path HKCU:\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover -Force
New-ItemProperty -Path HKCU:\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover -Name ExcludeHttpsRootDomain -Value 1 -PropertyType DWORD
Press enter and the commands will run. If you do not receive any red error messages, it has gone through successfully.
You can also set this registry key using the registry editor GUI.
Step 1: Open the Registry Editor
Step 2: Expand HKEY_CURRENT_USER | SOFTWARE | Microsoft | Office | 16.0 | Outlook | AutoDiscover
Step 3: Right click in the right hand panel and select new > DWORD, then enter the name ExcludeHttpsRootDomain
Step 4: Double click on the ExcludeHttpsRootDomain and then change the Value data from 0 to 1