Setting the Dunning Block in Customer Line Items 
If you prefer that an open item of a customer should not undergo a dunning procedure, even though it is overdue, you can set a dunning block in the open customer line items.
There are different options for setting a dunning block in an open customer line item:
The program is suited for mass programming. It can also be used for removing existing dunning blocks.
You can find the program in SAP menu under .