Opt-4's survey asked direct marketers to respond to questions from two perspectives, as professionals and as consumers.
As professionals, 63% felt that permission should be opt-out, but as consumers 61% felt that permission should be opt-in.
Around three-quarters of respondents believed that future opt-outs would rise.
If 5%, 10% or even more people decide they no longer wish to receive marketing material there would be a huge impact on the 拢27bn of business that the consumer direct mail industry generates, according to Opt-4 director Jenny Moseley.
Opt-4 is advising the industry to take action to reduce opt-outs by carefully wording permission statements and paying attention to consumer's attitudes.
The survey tested reactions to a differently worded permission statements, showing that different wording achieved differing levels of success.
Rosemary Smith, co-director at Opt-4, said: "Data protection statements are often an afterthought. This research confirms the impact that indifferent or poor wording can have on the level of opt-out. I would counsel any marketer to test their statements carefully to ensure the highest level of consent."
The survey identified empathy with a brand as the single most important factor in gaining permission to market.
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