Birmingham-based UK Mail - the first company to breach the Royal Mail's 400-year monopoly on the delivery of letters - has secured a major supply deal with the Royal Bank of Scotland.
Under the contract, which was for an undisclosed sum, UK Mail will collect and distribute mail for RBS - the UK's third largest bank.
Parent company Business Post said the contract would begin with immediate effect. In December, the company signed an agreement with the administrators of NCN, which runs a national network of independent express parcel delivery firms.
Under the agreement, Business Post has access to both NCN's centrally-serviced customers and its network members.
On the RBS contract, managing director of UK Mail, Guy Buswell said: "This is just one part of our strategy to grow exponentially over the next few years, which will of course continue to provide jobs at our mail hub in Heartlands."