Connect Microsoft Outlook 2019 to On Premise Exchange Server

https://justinho.com/blog/2018/12/31/Outlook2019OnPremiseExchange.html


Update 2023-09-01 (make notedpad doc - save as .reg - run and reboot)

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover]

"ExcludeHttpsRootDomain"=dword:00000001

"ExcludeExplicitO365Endpoint"=dword:00000001

[HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\office\16.0\outlook\autodiscover]

"ExcludeExplicitO365Endpoint"=dword:00000001


Need to use 'Advanced settings' on Outlook to select the option of 'Exchange 2013'

  • Open Outlook in safe mode
  • Create new profile, set as default and prompt for profile
  • Use non-cached
  • Profile should open
  • Cancel and password prompt and click 'need password'
  • Let it settle in
  • Close/open Outlook
  • Set new profile as default - want to make sure new profile is default

Make sure users are not signed into Office 365 (


Reference

https://www.alitajran.com/prevent-outlook-from-connecting-to-office-365/

Stop Outlook connecting to Office 365

To block Outlook from connecting to Office 365, follow the below steps:

Open Registry Editor as administrator on the client.

Prevent Outlook from connecting to Office 365 registry editor

Navigate to the below registry subkey. If you don’t see the AutoDiscover subkey, create the subkeys.

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover

Copy

The registry path corresponds to the Outlook version:

Outlook version Registry subkey version
Outlook 2016 16.0
Outlook 2019 16.0
Outlook Microsoft 365 16.0

Create a DWORD (32-bit) Value. Give it the name ExcludeExplicitO365EndPoint and the value 1.

Prevent Outlook from connecting to Office 365 add registry key

Restart Outlook on the system. Sometimes, you have to restart the system to have the change take effect.