Notifying customers with special order parts

So my question is are any of you out there doing anything in the parts dept to notify service customers that their parts have arrived at the dealership. Yes we have a BDC and apparently it is not putting a dent in our special order parts area. The service manager said that a very long time ago the Parts Dept used to mail out P9 cards that notifies the customer of their parts being at the dealership. Our Service dept already sends a plethora of emails to the cust just wondering what anyone here might be doing. Thank you.