How to create AD Distribution List using Identity Manager
You can use either the Provisioning Manager or the IM User Console to create AD Distribution Groups on the acquired AD Endpoint.
In the Provisioning Manager you would right-click on the acquired AD Endpoint and click on Content to then create a group.
In the IM User Console you would use the Endpoints->Manage Endpoint Groups->Create Endpoint Groups task.
You can review the following doc link too: