If it lands on the doormat, it is junk mail. If it turns up in your inbox, it is spam. And yet many schools seem happy to forward advertising material to parents on behalf of private companies selling DVDs, books, tutoring programmes and the like.
It is not hard to see why businesses are keen - it is the perfect way for them to reach their target audience. But what is in it for schools, and is it ethical?
Some would argue that if the services being marketed have a clear educational benefit, everybody wins. For example, many heads feel that private tuition can boost pupils who are struggling, and help to raise exam results. Schools are therefore often happy to work with tutoring agencies, by sending out promotional leaflets to parents and even allowing tutorials to take place in school.
Financial gain is another incentive. Companies that ask heads to forward material often make a direct payment to the school, or agree to provide free books or sports equipment. The payments aren't huge - typically between #163;70 and #163;150 per mail shot. But if a school acts on behalf of several companies, the money soon adds up.
"There is nothing intrinsically wrong with generating income this way," says ASCL general secretary Brian Lightman. "If the money benefits pupils, that is fine."
Even so, there are potential pitfalls. Local authorities urge schools to make it clear that they do not endorse the companies whose material they send out. Some even ask heads not to use headed notepaper when writing about commercial products. But does this really make a difference?
"I have forwarded leaflets in the past but wouldn't do so again," says Sarah Findlay-Cobb, head at Brinkworth Earl Danby's Primary in Wiltshire. "I always used to state that I was not endorsing the company. But on reflection, if the material is sent out by the school I think parents see that as a mark of approval."
Perhaps the best advice is only to send out advertisements if you endorse the product. "That is certainly my thinking," says Jim Courtney, headteacher of Great Sankey Primary in Warrington.
Mr Courtney distributes material for the Student Support Centre (SSC), a company that runs numeracy and literacy programmes - but only because he has trialled their materials.
"They fit well with our approach," says Mr Courtney. "Parents often ask for advice about extra support, and we are happy to make recommendations. It is part of the rapport between school and parents."
The problem, of course, is that if parents are unhappy with a product, they could blame the school. And researching different companies is a time-consuming task. "I'm inundated with requests," says Mrs Findlay-Cobb. "I can't possibly check them all out in the necessary detail."
Not surprisingly, businesses are keen to keep schools on board. Home tuition provider SSC is hoping to bring together companies which market through schools, and form a regulated group that adhers to a code of practice. This could require companies to demonstrate the quality of their products, or limit the amount of cash they can pay to schools.
"Very few heads agree to every marketing request - most will pick and choose," says SSC chairman Anthony Lee. "A code of practice should make it easier to determine which companies are ethical and responsible."
Suggestions for sales leaflets
Don't "spam" parents. Ask them in advance if they would be happy to receive marketing.
Always research the background of any company whose material you send out.
Produce an annual "directory" of products and services. That way you do not appear to be endorsing a single company.
Ensure payments received are transparent. Never accept personal gifts.
Don't put parents under pressure to spend money.