The postal group has launched Mailshots Online as a cost-effective means for companies to market to existing and potential customers, with prices starting from 55p per item.
The service comes as Royal Mail embarks on a strategy to attract more small business customers to use its services.
By visiting , small businesses can design postcard or letter campaigns, incorporating their own logos, images and text in four straightforward steps. Royal Mail then handles the production and delivery of the campaign.
Royal Mail business customers can either use their own databases to target their mailings, or use Royal Mail data.
Tim Rivett, Royal Mail's head of small businesses, said: "Royal Mail has a number of products and services that are designed to help the UK's small and medium sized businesses to grow.
"The launch of Mailshots Online comes at a time when fast, tailored communications is crucial to business success."
There is no minimum order-level for the service, which is being launched as Royal Mail shares the success stories and advice of 100 booming small UK businesses through .