In specific circumstances, when attempting to set up an account in Outlook, especially when attempting to connect via MAPI, you are prompted with an Microsoft 365 (Office) login screen. In most cases you can simply close this window and you're prompted with standard account login credentials. However, that may not always work.
This is because Microsoft's implementation of autodiscover in Outlook uses Office 365 as the priority location for a mailbox, irrespective of whether that mailbox is, or ever was, a part of an Office 365 implementation. This is where the "specific circumstances" come into play.
- If you're using Microsoft 365 (Office) for anything other than email. (E.g., just Office applications such as Word.)
- If you've used Microsoft 365 (Office) in the past for your domain, but no longer use it.
In both of these situations, it's very likely that Outlook will NOT move beyond looking at Microsoft 365 (Office) when checking the autodiscover for your mailbox. This is because Microsoft caches lookup data for domains, and if a domain is, or was, on Microsoft 365 (Office), that cache remains as the endpoint for an Outlook mailbox. If you've never used Microsoft 365 (Office) for a domain, but you see the Microsoft 365 (Office) login screen, simply canceling it (or clicking the X in the window to close it) will move on to a standard setup process.
However, there IS a workaround for this so that you can easily set up an account in Outlook:
- First, you'll want to remove the Profile from Outlook. If you're unsure how to do this, take a look at this KB article.
- Next, clear out ALL the data in C:\Users\[YOUR_USER\AppData\Local\Microsoft\Outlook. (Make sure you're able to View - Hidden items in File Explorer or you won't be able to find the AppData folder for your user.) NOTE: If you have multiple Outlook profiles, you can keep the existing OST files. If you created a profile for the account that is pointing to Office 365, simply delete that OST along with any other hidden files.
- Next, flush local DNS by opening a command prompt and running: ipconfig /flushdns
- NOTE: This might require that you open Command Prompt in Administrator mode.
Once this is done, you'll need to make two entries in your computer's Registry. Below is the change you will need to make. However, we know not everyone is comfortable making Registry changes. To alleviate that headache, you can download a zipped copy of a Registry (.reg) file
and run it on any computer you need to. It will make the Registry change automatically. NOTE: This shortcut will only work on computers running Outlook version 16.0. For older versions, the entries must be made manually.
- Open Registry Editor (be sure you're running it as an Administrator) and navigate to
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover. NOTE: If you are using an older version of Outlook, you must change the path to match the associated version. (16.0 = Outlook 2016, 15.0 = Outlook 2013, 14.0 = Outlook 2010, 12.0 = Outlook 2007).
- Add a new "DWORD (32-bit) Value" and name it: PreferLocalXML
- Next, Modify the new Value and change its "Value data" to 1:
- Add a new 'DWORD (32-bit) Value" and name it: ExcludeExplicitO365Endpoint
- Modify the new Value and changes its "Value data" to 1:
- After making registry edits, it's a good idea to reboot your machine. However, this step may be optional.
- Once each step has been completed, you can re-add your Account in Outlook.