Why do I recieve this error when sending as a delegate: "You do not have permission to send to this recipient"?

PROBLEM:

I recieve the following error when my users tries to send an email as WMA.Scanner account from their Outlook 2003 client.  

Error recieved:

The following recipient(s) could not be reached:

      Lastname.Firstname on 3/31/2008 10:13 AM
            You do not have permission to send to this recipient.  For assistance, contact your system administrator.
            MSEXCH:MSExchangeIS:/DC=com/DC=WMACE:WMAMAIL2

CONFIGUTATION:

Outlook 2003 / Exchange 2003

User has delegate permission as EDITOR for all Outlook areas such as Mailbox, Calendar, etc.

TESTS:
I can log into my Active Directory successfully as WMA.Scanner.
I can log into Outlook 2003 and send and recieve email successfully as WMA.Scanner.
I can log into OWA and send test emails to the organization successfully as WMA.Scanner.
I can view the WMA.Scanner email account from my two receptionists 2003 Outlook client.

I CAN NOT send email on behalf of the WMA.Scanner account from my receptionists Outlook 2003 clients. Start Free Trial