Nearly two thirds of people think the Fundraising Preference Service is a good idea, according to new figures from the research organisation nfpSynergy.
Researchers found that 64 per cent of the 1,000 adults surveyed in January said they thought the proposed service, which will allow people to opt out of all fundraising communications from charities, was definitely or probably a good idea.
Only 8 per cent said they did not think it was a good idea, and the remainder were unsure.
The proportion of people who would welcome the FPS rose in line with age: almost three quarters of those aged 55 to 64 thought it was a good idea, compared with 47 per cent of those aged 16 to 24.
Forty-two per cent of those in both the 45 to 54 and the 55 to 64 age brackets said the service was definitely a good idea.
Respondents were asked to choose from nine answers, such as "telephone and tell me about their work", to a question about what it was reasonable for a charity to do after they had made a donation to it.
About a third thought reasonable for a charity to write to thank them; almost a quarter chose "ask me for my permission every year to communicate with them again". Twenty-eight per cent of respondents said none of the answers were reasonable.
Seven per cent said it would be reasonable for a charity to ask for another donation after more than six months and 4 per cent said it was reasonable to ask within six months.
The survey also found that the charity sector was the highest of seven sectors for people saying they wanted to make a complaint about marketing, sales or promotion, but did not.
But it was among the lowest for people making an actual complaint about such activity. The highest level of complaint was about broadband services.
Joe Saxton, co-founder of nfpSynergy, said the figures on the FPS showed that its impact on giving could be "devastating".
"If these figures are right then a large majority of the giving public could sign up to FPS and cut them off from fundraising communications," he said.
"If 30 million people sign up to the FPS, the costs of the service will be very high and the impact on giving devastating.
"It’s clear the public want FPS; the question is whether it is the most cost-effective, fair and simple way to put the public in control of the fundraising communications they receive."