PO retransmission through FAX..

HI,

I am having one problem.One PO has been transmitted to vendor through FAX.It is transmitted through a middle ware.Now in ECC the status of of the transmission is showing successful.I have checked Message status in PO as well as also checked in SOST transaction.Both the cases the status is showing green.I have also checked with  the middle ware its also showing successful there.So now if client asked to retransmit those faxes again then please guide me how to do it?

I need to do repeat output in PO or I need to do any other activity in SAP or It will be retransmitted from middle ware.