Item-level MS Exchange Restore: 401 Unauthorized

Situation

The item-level restore plan for an Exchange database terminates with the following error: The remote server returned an error: (401) Unauthorized.

Cause

User credentials were entered using an invalid format during the restore, or the user is not granted sufficient permissions to place restored items into a mailbox.

Solution

Specify the username as username@domain.local, domain\username or user email address:

If this did not help, use administrator credentials instead of user ones.

Restored messages will be placed into the Restored mailbox of the user whose credentials were specified during the restore.