Abstract: An electronic transaction processing server receives and evaluates invoice transaction files. The server comprises a network circuit for communicating over a frame switched network with each of a plurality of participating systems. The participating systems comprising at least one customer workstation and at least one vendor workstation. A session management engine establishes a first secure session with a customer workstation and provides, to the customer workstation, a configuration document. The configuration document enables customer selection of evaluation parameters. The session management engine receives a post of the selected evaluation parameters and writes an indication of the selected evaluation parameters to a rules definition table. The session management engine further establishing a second secure session with a vendor workstation, receives an invoice file from the vendor workstation, and loads invoice line item values from the invoice file to records in a database.