One-third of people who make donations to charity are prompted to do so by receiving direct mail from the organisation in the post, according to a survey by delivery company TNT.
The poll of 2,000 British adults found that 57 per cent of those who respond to mail appeals do so by post.
It also found that 10 per cent of respondents would use information sent through the post to find out more about a charity, but 87 per cent of people would go online.
Cathy Pharoah, director of the Centre for Charitable Giving and Philanthropy, said it was important for charities to develop an integrated multimedia approach to fundraising.
This should include online avenues, mobile phones and texts, as well as more traditional methods such as post, she said.
"Direct mail may not always be the most cost-effective way for charities to fundraise, but it is still a hugely important way for charities to get their message out. It is particularly important for the many donors who still prefer to give through cheques sent in the post," she said.
Nick Wells, chief executive of TNT Post, said: "This survey shows that direct mail or door-drops, both on their own or part of a multimedia strategy, continue to deliver results."