SymptomsTask for mailbox initialization in Exchange 2003 organization fails with the following error:
Cannot fetch URL:'http://192.168.1.123/exchange/', HTTP error: 'Unauthorized' (HTTP error code: 401)
CauseWhen POA creates a mailbox, it is created on one of the available AD domain controllers (POA tries to use preferred domain controller) and then replicates to another controllers. This replication is not instant and can take some time.
Just after creating a mailbox POA schedules a task on initialization in order to make sure that the mailbox is operational - until this task completes, this mailbox is not marked as "Ready" in the control panel. The task tries to login to OWA with the mailbox owner's credentials and can fail due to replication issues.
ResolutionSuch tasks are rescheduled automatically and usually complete in 2-3 runs, but they can also fail due to various Exchange or AD related issues.
If a task got "Failed" status finally after several execution attempts, it should be run manually in order to confirm that the error persists. In case the task keeps failing one should check if OWA is working on the corresponding server and investigate possible AD replication issues.