Note - You are still required to Receive Purchase Orders even if a Paperless Invoice has been received. See: Receive Goods against a Purchase Order

Invoices (manual or electronic) that match a Purchase Order will automatically go through the 3-way matching process between the Purchase Order, Goods Received Note, and the Invoice. 

If all three documents match, the Invoice will go straight to the Reconciled Invoices section - ready to be processed for payment by the Accounts Department.

If the documents don’t match, the Invoice will be 'Flagged' for further approval. See: Approve Flagged Invoices

The diagram below explains how the 3-way match works in more detail.