For SRM PO, whenever we make a change the email goes to the vendor but for few changes we want to stop the email going to the vendor so thinking to delete the entries from table PPFTTRIGG but not able to link the GUID of PO with OS_GUID of table PPFTTRIGG.
I recommend you to check the following wiki page regarding to this topic:
You can set up the table BBPV_COMP_FIELDS to avoid a new Purchase Order Output to the supplier. You can use this table to exclude fields from the comparison, that are not important in your purchasing process. If you exclude a field from comparison, the output will not be generated, if that field changes.
I hope this will help you to set up the output of the SRM PO.