Getting PDF documents into OnBase quickly and easily

There was a time when almost all documents were paper and they were stored in file cabinets, taking up a lot of space.  Then we took those paper documents and scanned them into a document management system so that users could easily access them from a computer.  Now in many cases these documents are electronic and we are challenged with getting them into our ECM solution so that they can be widely accessed by people all over the globe.  Companies take these electronic documents such as invoices and send them to customers via email to save on the costs of postage and reduce the time it takes for them to receive it.  Systems now have the capability of printing information to a PDF document, for example an accounting system can output a document with all the invoices that were processed on a given day.  How can these invoices get into the system without printing, scanning and indexing?