The Direct Mail Information Service claims that charities using direct mail to target donors have an average response rate of 13 per cent, one of the highest of all business sectors.
But the figures are set against Mintel's Market Intelligence report on charities, published in January, which found only 3 per cent of people had begun a direct debit or standing order as a result of receiving direct marketing, and that it was the least popular mechanism for giving among consumers.
The Charities Aid Foundation reacted to the DMIS figures with surprise.
"This does seem rather high," said Cathy Pharoah, research director at CAF. "We know that most ordinary mail surveys are struggling to get more than a 10 per cent response rate."
But Fraser Chisholm, head of media developments at the Royal Mail, defended the figures. "Response rates are not an exact science," he said. "The main thing to consider is that direct marketing works well to capture donors, especially when combined with TV advertising campaigns."
DMIS, the research arm of the Royal Mail, also published figures that showed charities spent more than £691m in direct mail activity in the last quarter of 2005, up 2.5 per cent on the same period in 2004.