While working with a customer who was searching for a solution to help manage distribution groups, I discovered that Exchange provides a feature called Dynamic Distribution Groups. These groups allow you to set up the distribution group, and then create a rule that references something like an OU or an AD account property to define which users belong to that group.
Here is a link to the TechNet article about Dynamic Distribution Groups:
https://technet.microsoft.com/en-us/library/bb123722(v=exchg.160).aspx