Zadspace places peel-off 6x4in adverts, known as Zads, on delivery packages, mixing direct mail with the benefits of transpromotional marketing.

The adverts are printed on-demand at the point of shipping and each advert is triggered by timely transactional data to ensure it is highly targeted.

During a year-long beta trial, in which 500,000 Zads were printed for more than 100 campaigns from 25 advertisers, the company claimed that not only did the medium outperform direct mail, but also packaging inserts 12-fold.

Zad chief executive Todd Outten said: "Direct mail competes with all of the other impressions that arrive in the mailbox. The Zad has a virtually guaranteed read-rate, and it rides along with the fulfilment of an anticipated b2c transaction. It's a powerful combination of pristine placement and perfect timing."