Roy Hathaway, head of waste at Defra, told the conference that "it's all to play for" and that it is up to the industry itself to prove it can succeed in achieving its next recycling target.
Hathaway said that PAS 2020 could only have a real impact if taken up by individual companies within the industry and therefore the ball was firmly in the industry's court.
He stressed that in the current economic climate it was even more important for the DM industry to achieve resource efficiency and waste prevention both in its own operations and in what it sends to customers.
Hathaway praised the DM industry for the rise in recycling of addressed mail and the increase in awareness of the Mailing Preference System but pointed out that volumes of unaddressed mail still needed to be tackled.
He also praised the DMA's Your Choice scheme, launched in April 2008, but said that it had not been widely publicised and so take-up had been low.
Justin Basini, vice president of brand marketing at Capital One Europe, urged marketers to seek PAS 2020 accreditation.
He recounted the journey Capital One has taken over the last three years to move away from direct mail to a more integrated marketing mix. Last month it was revealed that Capital One axed direct mail as an acquisition channel.
The company has succeeded in moving down from the number three direct mailer in 2006/7 to 53rd on the list.
Basini said that after facing huge consumer resentment to large volume direct mailing Capital One did a full carbon assessment, under a programme it rolled out globally called 'Our Choices Count', to understand how to make progress as a corporation.
It discovered that consumers had started to change their behaviour from once going into a branch to buy a credit card to favouring the internet to make purchase decisions.
This led to Capital One adopting a more integrated marketing approach to drive efficient consumer response. As a consequence its internet position changed from the 35th to the 4th biggest internet marketer.
Basini described it as a "win win" situation because as well as achieving a reduction of 9.970 tonnes of CO2 between 2007 and 2008 Capital One had also seen that marketing efficiency has increased as it understood the consumer better.
Harry Cooklin, marketing communications manager for Honda UK, said the car maker's relationship marketing could be described as "inherently green".
Since 2002 Honda has reduced the costs of its direct marketing activity, the amount of landfill it produces and reduced its carbon footprint.
Cooklin said that most importantly it had also resulted in happier customers.
BSkyB was the first media company in the world to become carbon neutral in May 2006 and Jo Fox, head of environment, accessibility and corporate responsibility, revealed how it achieved this and new initiatives the company is working on.
In terms of paper communications, BSkyB switched to more targeted mailing, changed to 100% recycled paper for all internal communications, and printing customer communications and direct mail on recycled FSC or PEFC sourced paper.
This year Sky is looking at what else it can do and has become the first customer to work with TNT and the Carbon Neutral Company on their carbon neutral mailing programme.