American Express and MineralTree have created a platform that lets midsized companies automate the supplier payment process from invoice to remittance, an option previously available only to larger enterprises. MineralTree, an accounts payable and payment automation provider, considers midsized companies to be those making between 50 and 10,000 payments a month. Amex applies the term to companies with annual revenue between $10 million and $1 billion depending on the industry, geography, and other factors. By either measurement, companies in the midsized category use paper checks to settle app...