The Gateshead-based business, which printed the mailer on its Heidelberg Speedmaster CD 102 using Cyclus stock, said the pack was eligible for a 4.7% discount on Royal Mail delivery costs as it matched the Sustainable Mail's environmental criteria, which was launched in April this year.

Qualification for a discount means using only paper products from measurable sustainable sources that must be approved by Central Point of Expertise in Timber and must be fully recyclable. They must be produced using non-chlorinating bleaching methods and sourced from mills that operate an environmental management system.

The cost reduction available with Mailsort 120 or 700 is 2% for entry level and 4.7% for intermediate level. This percentage reduction is applied to the Mailsort price after all the normal Mailsort and volume-related discounts have been applied.

John Horn, NB Group customer services manager, said the company was "thrilled" to get its first campaign approved under the new Royal Mail product for environmental sustainability.

He added: "We've been working very hard to minimise our environmental impact for a number of years now, and meeting the Sustainable Product's criteria so quickly after it was established shows just how keen we are to continually improve our green performance."

Each of NB Group's mailers were designed to resemble a handbag, with the aim of encouraging customers to visit the TK Maxx website for discounted designer handbags.