Felicity Donor, the Third Sector blogger, started quite a debate last month when she declared that charities shouldn't waste money on "fluffy thank-you letters".
Her views are widely shared: the British public is massively illogical in how it regards charity expenditure.
But in her book Tiny Essentials of Raising Money from Foundations and Trusts, Jo Habib, director of FunderFinder, says: "Any fundraiser who doesn't thank donors properly is an idiot as well as rude."
I agree with Jo. Of course it's rude, and foolish, for a charity not to acknowledge every gift it receives and reassure the donor that it's been put to the intended use.
Imagine if, as a child, you never acknowledged the socks or diaries your grannies and aunties provided without fail, year in, year out. No more socks and diaries. Ever.
Yet 'mystery shoppers', who provide feedback to the sector on customer service, consistently show that as a profession we are truly crap at saying "thank you" properly, and at reassuring donors that their gifts have been safely received and wisely applied.
And then we wonder why we can't keep our supporters. Perhaps we don't deserve them.
The simple fact is that an appropriate thank-you letter is perhaps the best fundraising opportunity of all. If it can convert a first-time donor into a regular giver, then surely thanking people is a no-brainer.
A prompt response that properly acknowledges the gift cements the relationships between charities and donors. This is blindingly obvious. The commercial value of timely and careful thanks has been shown time and time again.
The fact that people still share Felicity's view is our fault, not theirs.
The only reason that a donor might think a charity should not send a polite note of thanks is that we've allowed them to imagine otherwise. We are fools for not rectifying this misconception quickly.
Some charities persist in saying they will thank donors only for gifts of more than £10, or only if the donor specifically asks for acknowledgement.
So the unappreciated donor can hardly be blamed for leaving the residue of their estate to some other, more polite and perhaps more deserving cause.
Of course I don't want to inconvenience my children by asking that they write me thank-you letters for my sacrifices in their direction over the years. But if they don't show appreciation, I certainly won't do it again.
FACT FILE - You're welcome
Research by consultancy McConkey-Johnston International UK found that first-time donors who receive a personalised thank you within 48 hours of making a donation are four times more likely to give again than those not thanked promptly.
One of McConkey-Johnston's clients, who recently started sending thank-you letters to donors, has seen the retention rate of regular givers climb from 86 to 93 per cent.
Eighty-three per cent confirmed the donation on the day it was received and all but three of those said 'thank you'.
Fundraising consultancy John Grain Associates found in 2008 that 14 charities out of 25 failed to acknowledge a £10 gift in any way.