The Exchange Web Service (EWS) URL associated with the mailbox could not be located. This may happen for the following reasons:
- The account does not exist or has no provisioned mailbox.
- The mailbox was created recently and it takes time for replication to occur.
- The mailbox is associated with an F1 or F3 Microsoft 365 license, which limits EWS access.
- Microsoft 365 discovery services returned an empty response.
Verify that you can log in to the mailbox via the Microsoft 365 web portal (portal.office365.com). If using administrative credentials:
- Log in to the administrator's mailbox.
- Click the user name at the top right corner.
- Click Open other mailbox.
- Enter the email address associated with the mailbox.
- Click Open.
If the mailbox is associated with an F1 Microsoft 365 license, which was re-branded to the Microsoft 365 F3 license in April 2020, and you are not using administrative credentials, consider specifying administrative credentials on your connector. F1 mailboxes have limited access to Exchange Web Services. Using administrative credentials can work around this limitation. Make sure the admin account has impersonation rights configured.
If the mailbox is not associated with an F1 or F3 Microsoft 365 license, confirm that Microsoft 365 discovery services are responding properly by testing access on the Microsoft connectivity test website.
Finally, if the user/mailbox was created or had a license applied in the last 24 hours, it is possible that replication through the Microsoft 365 infrastructure has not yet completed. There is no way to tell if this is the issue other than waiting until 24 hours has passed and then trying the migration again..