It has also accredited Experian as a preferred supplier of business-to-business marketing information.
Royal Mail handles more than 420,000 different business accounts ranging from high-street names to sole traders.
Richard Lloyd, managing director of Experian's business information division, said: "Because we combine our business and consumer data on business owners to provide a more complete picture of small businesses and sole traders and their financial behaviour, our clients can count on us to provide more complete coverage of the UK business population."
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