Hi Eliud,
You don't need a content filter. First, you must create an interface group. In CLI, run "interfaceconfig", then "groups", "new". Give your new group interface a name, and list all the interfaces you want to include for round robin delivery.
Once you have the group configured, issue "deliveryconfig" command, "setup", and set delivery to use the newly created group.
If you want just *some* messages to be delivered round robin through multiple interfaces, then skip the deliveryconfig part, and create a content or message filter that will use altsrchost() ("Deliver from IP interface") action.
Hope that helps!
