Barcode Recognition

About a year ago, my company purchased a document imaging system (OnBase). We want to add barcodes to our documents that we send out and expect to be returned so we can use them to auto-index after scanning (Kofax scanning software). The problem we are having is that the largest barcode font(3 of 9) we can fit on our letters is 18pt(we have 3 barcode per document). We have continued to get inconsistant reads at this size. After researching, I found a website that stated that in order to getconsistant reads, you need to use at least 24pt to 28pt. That is a pretty big barcode and would not look real good on a business letter. Has anybody tried anything similar to this and had success with a barcode 18pt. or smaller? If so, I would love to know what you did to accomplish this.