The organisation is encouraging responsible production and use of print and paper, and seeks to dispel common environmental misconceptions that damage its environmental record.
TNT Post Doordrop Media managing director Mark Davies said: "We are delighted to join Two Sides, which we see as delivering a really important message about mail’s sustainability.
"TNT Post UK has an absolute focus on reducing our environmental impact and working with Two Sides will help us to reinforce our commitment to promoting the sustainability of our services."
The company already has a number of environmental initiatives underway and saw Two Sides as a natural addition.
It developed the first carbon neutral initiative for addressed mail in conjunction with The CarbonNeutral Company and has launched GreenPost, a service aimed at producing environmentally-friendly promotional direct mail, and DataMatters, which enables clients to clean or suppress data, reducing direct mail wastage.
Two Sides director Martyn Eustace said: "Having TNT Post UK on board is great for Two Sides and demonstrates the involvement of major players right across the print media value chain.
"There is much misinformation about the sustainability of mail and by working with TNT Post UK and others, we aim to ensure that consumers see that mail can be a highly sustainable way to communicate."
