In the Waste Strategy white paper, published yesterday, the government stated it will pursue measures to "develop an opt-out for unaddressed mail with the DMA", but said it will "explore the scope" for opt-in mechanisms.
However, the DMA has warned that changing to an opt-in regime would severely impact on the direct marketing industry, consumers, and the Royal Mail's ability to operate at a competitive price.
In a statement, the DMA said: "Without the revenue generated by direct mail, the ability of Royal Mail to maintain a universal service at a competitive price to the consumer would be severely under threat."
It added that a "significant number of jobs" depended on the direct mail industry, and questioned whether the proposed clampdown would extend to the government's own party political communications.
The DMA said it supported the consumer's right to say no, citing its decision to voluntarily set up the Mailing Preference Service, but conceded the industry now faces "a number of challenges to change behaviour".
The DMA now plans to set out a number of major initiatives involving government-sponsored organisations and charities to address consumers' environmental concerns.
It will meet with ministers from the Department for the Environment, Food and Rural Affairs (Defra) next month to further discuss proposals made in the Waste Strategy white paper.