Autodiscover Process for a Migrated Office 365 Mailbox

Once a mailbox has been moved to Exchange Online, but co-existence is still required, then Autodiscover will remain resolving to on-premises resources. For these migrated mailboxes, this means the Autodiscover process is a little bit more complex than normal.

The following image shows the output of the Outlook Auto-configuration Test tool for a mailbox hosted in Office 365.


1. Autodiscover URL is found using SCP
2. Attempt the supplied Autodiscover URL
3. Authentication successful
4. Autodiscover not successful as the mailbox is in O365 (0x800C8205)
5. New URL attempted, based on the Target address attribute
6. Error 2147954407
7. URL not found Error 0x80070057
8. Tries the next URL
9. Error 2147954429
10. Error 0x80070057
11. Local lookup starts
12. Local lookup fails 0x8004010F (as it is not local)
13. Redirect check to
14. Redirect to (HTTP to HTTPS)
15. Starts request
16. Authentication required
17. Authentication successful
18. Request succeeded
19. XML data received

This is quite a drawn-out process, but can be summarised as follows:

1. Find local info via SCP
2. Try supplied URL
3. Connects successfully, but mailbox is not local (in O365)
4. Tries URL based upon the target address (O365)
5. Redirected to HTTPS (O365)
6. Autodiscover connects (O365)

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