Four years ago, several thousand residents in the state of New York opened up a piece of junk mail only to be hit with an unexpected sensory assault – the smell of actual junk. Republican gubernatorial candidate Carl Paladino had produced landfill-scented leaflets with the headline “Something Stinks in Albany”, a broadside aimed at his political opponents. “When the oxygen hits the card, the stink starts,” he explained, proudly, to the CNN news channel in 2010.

We’ve all sifted through piles of unsolicited letters; few annoyances are as universally bemoaned. Junk mail now accounts for almost half of all mail delivered in the US. But as Paladino’s smelly letter showed, it can be surprisingly innovative. It’s far from the only trick that mailers have used too. Direct marketing firms employ a variety of hidden, often subliminal, techniques to encourage us to notice and read their missives– and hopefully go on to buy something. Knowing what these tricks are may change how you see the leaflets and letters popping through your door.

For those in the business of direct marketing by post, the term “junk mail” couldn’t be further from the truth. “It’s only junk if it’s not relevant to you,” explains Belinda Neal, a partner at London-based direct marketing agency 21:12. “And if it’s not relevant, that’s due to poor targeting.” These days, although blanket mailings still occur, the real money is to be made in areas where direct mail can be customised for each recipient.

Targeted for you

The data collected about what you buy is increasingly granular and marketers are able to send promotions and offers out to specific audiences. For example, Nectar, a loyalty card scheme in the UK, sends customers of the supermarket Sainsbury’s offers on specific items they had previously bought in store – right down to their preferred pasta shapes.

What’s more, the very design of postal advertising can be personalised for each recipient. Everything, from the text to what pictures are included, is varied. “It’s realistic for a mailing to go to over 10 million people with over five million different permutations because everybody gets different things based on the data that we’ve got,” according to Jonathan Harman, managing director of The Royal Mail’s MarketReach business.

Harman explains that his current favourite direct mail campaign is the one by home improvement retailer Homebase. Wall tiles and fittings, for example, were suggested as future purchases if a customer had recently bought a kitchen. Each mailing was individually personalised and delivered within six days of the original purchase. This type of marketing improved Homebase’s sales for the year by 2%, or £30.4m ($48.6m).

Even the weather can have an impact. Home furnishings giant IKEA’s direct marketing campaign for garden furniture was delivered during sunny spells. The result, they say, was 34% higher sales of outdoor products.

Paper tricks

Marketers also experiment with the way the physical mail is presented to beguile us in surprising ways. Slightly thicker paper, suggests Jonathan Harman, can make a letter feel more important so recipients are likely to give it better attention.

This is where we enter the nitty gritty of direct mail and a phenomenon called A/B testing, where subtle changes in design are tested on small audiences, in parallel, to see which provokes a better response. A/B testing is used extensively these days by website owners in order to optimise web pages, encourage users to spend more time on them, or click on a greater number of links. But curiously enough, the origins of this technique lie in the world of direct mail.

Through years of testing, Neal and fellow marketers have discovered all kinds of interesting cues that increase the impact of unsolicited post on sales. Stuffing an envelope with gifts or physical items makes people more likely to open it, for example. Sub-headings help a reader understand what the letter is about at a glance, says Neal, while ending the first page mid-sentence so that readers are encouraged to continue reading has become a tried-and-tested technique. Even the use of a “P.S.”, in which the recipient is prompted to get in touch with the company and make a purchase, has been systematically evaluated. “We have tested with and without P.S.’s,” says Neal, “and it’s just best practice now.”

While some direct mail is designed to stand out from the rest of your post, arriving in a snazzy or colourful envelope, other forms take a different approach and try to blend in so as not to be immediately discarded as “junk”. Neal says this can be achieved by using plain envelopes and paying to have actual postage stamps on them even though mass mailings are usually sent at a discounted rate without stamps. Lasers can also be used to inscribe a handwritten-style addressee on the front of the envelope. All these methods help to achieve a level of realism that may improve the impact of any given mailing.

A/B tests on direct mail have also come up with some insights that are difficult to explain. According to Neal, for certain clients application forms with a blue background seem to perform better than forms using a different colour. No-one’s quite sure why.

Sometimes, though, it’s about simply delivering something that people haven’t seen in their post before - like Paladino’s smelly leaflets. Jason Andrews, executive creative director at creative agency RAPP UK explains how he once helped the British Red Cross charity come up with a mail campaign drawing awareness to destitute people in central Europe facing a particularly harsh winter. A message written in temperature-sensitive ink would only appear when the letter was placed in a freezer for several minutes.

“The only place in Britain where it felt that cold was actually in people’s deep freezes. So you would put the letter in there, get an idea of what it was like,” explains Andrews. “That’s what these people were putting up with without food, heat, clothing and so on.” While it was a bit of a gimmick, it shows that it’s still possible do novel things with the old medium of paper and envelopes.

Tangible products

Understanding the special relationship we have with physical post is now integral to the design of these campaigns. Harman’s work at The Royal Mail is largely to do with investigating how people consume mail when it comes into their home. This has been done by setting up cameras in people’s hallways and recording what they do with letters when they arrive.

“On average, mail will stay in the home for 17 days,” says Harman. “So there’s a real permanence to what we do. We also know that people pass on mail that they think might interest their friends or relatives.”

Harman has even looked at what happens to our brains when we read a letter addressed to us. While it may be worth taking these findings with a pinch of salt, analysis of brain activity revealed that post stimulated parts of the brain associated with long-term memory and also involved more emotional processing than virtual media. It’s perhaps not surprising, then, that brands are continuing to invest in sending physical leaflets despite the lower costs promised by email and other digital communication.

Finally, Harman and others also rely on technology which simulates human “eye-tracking” – the precise way in which we scan a page when we first look at it. A machine can suggest, to a high degree of accuracy, how a human will visually survey any document at first glance. Art designers use this to position the most important elements of the message accordingly, so that they are read first.

Ultimately, those working in the industry aim to target and design their mailings with as much sophistication as possible. Harman, like Neal, rejects the term “junk mail” and argues that it’s old-fashioned.

“It feels to me like it’s professionally crafted, it doesn’t feel like junk at all,” he comments. “[The term] goes back to the days when marketers were less discriminate. But as other cheaper channels have opened up, perhaps the junk mail of yesterday is today’s spam email.”

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