Hello,
error messages come from message class SPPF_MEDIA: it is linked to address number (CL_SF_MAIL_PPF class).
In BBP_PD transaction, check if your supplier partner has an adresse number (ADDR_NO).
Check in PPOSV_BBP transaction for concerned supplier if "Supplier Address" tab is populated. You can also check BUT052 table with 'PARTNER1' populated with your supplier BP number: It will give you the address number.
Regards.
Laurent.