Forward emails to multiple recipients using Microsoft Exchange Server
Although Microsoft Exchange (5.x+) offers the possibility to forward emails to single recipients it is sometimes necessary to specify a whole list of recipients. Fortunately, in order to achieve forwarding emails to multiple recipients using Microsoft Exchange Server you only need to create a distribution group via the Active Directory management interface.
Be sure when creating the new group to select “distribution” as group type. Once created, add as many accounts to this group as needed. Emails to this group will be automatically distributed among its members.
As you might have realized already, the last step is to set this distribution list as single forward recipient in the Exchange settings tab of the account. More detailed information can be found here: http://support.microsoft.com/kb/251631