Turns out after doing some further research that multiple Exchange Servers running in the same domain do not need any new configuration.
The only thing I had to do was add the correct BES privileges to the new Exchange 2007 Server:
You need to run the following shell command on all of your Exchange 2007 servers:
get-mailboxserver <mail_server_name> | add-adpermission -user <service account> -accessrights GenericRead, GenericWrite -extendedrights Send-As, Receive-As, ms-Exch-Store-Admin
e.g. Server 1
get-mailboxserver bbforumsex01| add-adpermission -user BESadmin -accessrights GenericRead, GenericWrite -extendedrights Send-As, Receive-As, ms-Exch-Store-Admin
e.g. Server 2
get-mailboxserver bbforumsex02 | add-adpermission -user BESadmin -accessrights GenericRead, GenericWrite -extendedrights Send-As, Receive-As, ms-Exch-Store-Admin
|