How can I automatically create DLs?

Create DLs from a predefined list
Let's say you have a list of names that came from your human resources (HR) database, and you want to assemble the names into a DL. Using Exchange Administrator's directory import and export commands is the easiest way to make this DL. Use the create mode, and specify that you want to add a DL, using a header such as "insert code here."

Create DLs based on group membership or some other directory attribute

You can create the DL yourself with Lightweight Directory Access Protocol (LDAP) or Collaboration Data Objects (CDO), but that's a lot more effort than most people want to expend. Instead, you can use a tool called the Rule-Based Distribution List (RBDL), which is included in the Microsoft BackOffice Resource Kit (BORK). Microsoft doesn't officially support RBDL, and it doesn't always work.)