The statutory review of the business, which is currently held by Bates UK, will take place ahead of the removal of competition barriers in the UK postal market. This is likely to happen in the next two years.
The review, which is being handled by Gillian Wilmot, Royal Mail's managing director of business and consumer markets, will take place this autumn with appointed agencies selected on a two-year contract.
Bates' recent UK work has run under the strapline: "The real network." Its last campaign continued the strategy weighted toward business customers.
It promoted Royal Mail's special delivery service with a silver sphere rushing through the air around famous UK landmarks to represent a Special Delivery parcel.
The ad review coincides with a difficult time for Royal Mail, which recently announced large-scale redundancies following a review of its operations by Allan Leighton, the new chairman of its parent company, Consignia.
The Consignia name will disappear later this year to be replaced by Royal Mail Group.
Earlier this year Consignia completed a review of its media account, with the incumbent, Carat, retaining the planning and buying business.
Royal Mail is currently putting forward proposals to change its price structure for its business mail services. Direct marketing agencies have reacted strongly to plans to move toward a pricing system based on the shape and size of mailings rather than weight.