Pitches for the project are due to take place in early June.
The process will not affect Royal Mail’s existing agency relationship with Beta. The agency has held the integrated advertising account since 2011, when it beat J Walter Thompson London, McCann London, MWO and Y&R Brands in a pitch.
Publicis Chemistry will continue to handle the direct marketing account, which it won in 2013. In January, it launched a campaign for the company called "mailmen" that featured Karen Blackett, the UK chief executive of MediaCom, and Robert Senior, the worldwide chief executive of Saatchi & Saatchi.
Royal Mail was privatised and floated on the London Stock Exchange in 2013, although the government still owns a 30 per cent stake. Royal Mail staff own 10 per cent of the business.
Earlier this week, Royal Mail awarded its main media business to Arena and the MarketReach media account to MC&C. This ended a three-year relationship with Interpublic’s UM London.