Wilmot, who is managing director of Royal Mail Business and Consumer Markets, and Novak, the Media Markets unit managing director, are to see their departments combined with the E-enterprise unit to form a Letters division.
This new unit will run all Royal Mail customer-facing activity and have a marketing budget worth up to 拢80m. The group restructure will affect more than 160,000 staff.
Both Wilmot and Novak have featured in Marketing's annual Power 100 league table of the UK's top marketers.
The Letters unit will be led by a single managing director, tipped to be Royal Mail group managing director Jerry Cope, and one marketing director.
While Wilmot and Novak are likely to be in the frame, Royal Mail said no personnel decisions had been made.
Other units will include logistics, Parcelforce Worldwide and international.
Each will have their own sales and marketing functions.
The restructure has been triggered by financial problems resulting from the opening of the postal market to competition.