The company is inviting tenders for three contracts: brand strategy and services, worth up to £4m annually; above-the-line marketing services, also worth up to £4m in billings; and below-the-line marketing services, on which it spends up to £5m a year.
Each contract will last for four years. Incumbents AMV BBDO, Wolff Olins, and direct marketing shop Proximity London are all being invited to repitch.
Earlier this year, media agency OMD UK picked up the £18m Royal Mail media account, after a statutory review. The business had been with Carat for 10 years, which pitched against PHD and MediaCom for the account.
The request for tenders comes as Royal Mail waits to find out if union members will agree to a deal it has struck over pay, pensions and the modernisation of the service. If members oppose the deal, it could lead to more postal strikes.