If you want to streamline part of the Accounts Payables processing, why not let your vendors post their invoices themselves through the Vendor Portal rather than with a stamp through the USPS. Through the portal they are able to enter in all of the billing information and line details, and also attach any supporting information as document attachments that will then show up within the Payables area page as pending invoices. The invoice then just needs to be reviewed and approved and it will be ready for payment.
You will become more efficient, because you don’t have to re-key in invoice details as they arrive in the paper format, and also the vendors should be happier because you will be able to pay them sooner because there isn’t any lag between the invoice being posted and it being available for review for the payables group. Everyone’s a winner.