eMailing PO

We are on R12 and using iProcurement for one vendor to order office supplies, these requisitions are converted into PO and sent to the supplier automatically. Now we want to implement smart forms to create requisitions and turn these into PO and send to the supplier automatically. Everything is working fine except the PO is not getting email automatically once approved. I have checked the supplier setup and the email is there and the correspondense is setup as eMail. Am I missing something else?

Thanks