When you order a Purchase order you would get this error.
You may notice that in the edit out put settings of purchase order you have chosen other out put channel other than email but you still see this error
SAP Business ByDesign
The email address maintained in supplier master data is not valid.
Please open the supplier master data and maintain the correct email address.
email address error, , KBA , SRD-SRM-PRO , Purchase Requests and Orders , AP-POP-PO , Purchase Order , Problem