It has approached a number of agencies, with a view to holding a pitch for the business later this summer.
The winner will be responsible for handling a series of DM campaigns to raise awareness of the charity and the work it undertakes.
RNIB has not had a retained DM agency in recent months; however, it has previously used Rapp to handle some DM and strategic data work.
St Luke's, the charity's advertising agency, and Meteorite, which works on RNIB's fundraising account, are unaffected by the pitch process.
Last month, Meteorite launched an integrated campaign based around its Really Good Read fundraising event. The campaign encouraged people to host book-themed events to help raise funds.
Last year, RNIB bolstered its data management capabilities by appointing Occam to work on ways to improve its marketing database.