Limit users in Custom Global Address List (Exchange Server 2007)

Hi,

I am trying to create a separate Global Address list to limit our hourly employees to only be able to see the Mailbox users inside our organization. I want to exclude Mail Contacts, Dynamic Distribution Groups, and Public Folders. I tried the following command in Exchange Management Shell but received an error:

Set-GlobalAddressList “Custom Global Address List” -RecipientFilter {(Alias -ne $null -and RecipientType -ne ‘MailUser’ -and (ObjectClass -eq ‘user’ -or ObjectClass -eq ‘Contact’ -or ObjectClass -eq ‘msExchSystemMailbox’ -or ObjectClass -eq ‘msExchDynamicDistributionList’ -or ObjectClass -eq ‘group’ -or ObjectClass -eq ‘publicFolder’))}

The error was: Property RecipientType used in the filter has unsupported operator NotEqual. 

We are running Exchange server 2007 SP1.