How to reject the Purchase requisition

Hi

We have sceanario , where we are creating Purchase requsition in Planning dept & after releasing those PR , we give it to Procurement dept for making the Purchase Orders

Due to some reasons , if Purchase dept is not able to make the PO due to any defects in PR (non SAP issues) , they want to inform back to planning dept about the same .Currently they are giving the e mail abt the same . Do by any method , can they reject PR (or its line item) in system , so that they doesn't have to send the mail & planning dept automatically come to know abt the rejection of PR & its reason thru system itself

rgds

sandeep