The Cisco Unity IP fax wizard encounters problems with inbound faxes even though the messages come into the defined mailbox on the Cisco Unity server. Faxes arrive through the router and go into the common inbound mailbox (UnityFax). However, the fax service is unable to route the message to the appropriate user mailbox.
The log file for the fax service contains the CIpFaxCdoHelper::LogonToMailbox() name returned from Logon is [Unknown] error message.
This problem can occur if the recepients of the fax or their fax mailboxes are hidden.
Check whether the users or mailboxes that are the intended recepients of the faxes are hidden. If so, perform these steps:
Select Start > Programs > Administrative Tools > Active Directory Users and Computers.
Select View > Advanced Features.
Open the appropriate user accounts.
Select the Exchange Advanced tab.
Check whether the Hide from Exchange address lists check box is checked. If so, clear the selection to resolve the problem.