This is intended to add value to its service, by allowing firms to track bulk mail consignments through to delivery round, information which previously had only been available through higher cost tracked services.

Firms will have to apply their own barcodes, but will get access to daily online reports detailing which mailings have been processed and sent out for delivery.

The service will be rolled out in January 2014.

The DVLA and retailer N Brown are two of the 47 companies already signed up, that collectively send more than eight million items of mail a day.

The investment is part of Royal Mail’s strategy to manage structural changes in the letters market, which will continue to be an important source of revenue for the business.

It says the core letters business is key to its financial success, generating almost £4.8 billion in reported revenue during the 2012-13 financial year. Royal Mail’s letter revenue increased by three per cent on a like-for-like basis in that period.

This follows several moves the group has made to improve its profitability as it prepares itself for privatisation. This has included increases to its prices with particular impact on certain size and weight bands.