PO message should get failed for P.grp other than AB1 and AB2

Hello SAP Gurus,

I have a requirement like PO message should get failed for P.grp other than AB1 and AB2.

Detail explanation:

I have a P.grp AB1,AB2,AB3,AB4 etc.... The current process is once PO created and saved the message will be triggered and IDOC is transmitted to the vendor, irrespective of what ever the P.grp.

My requirement is like the PO message should get failed if P.grp is other than AB1 and AB2, and reason should be shown any where in IDOC or in messages.

Pls advice.

Thanks.