Junk mail. Paper spam. It goes by many names, and most of them are disparaging. But Direct Mail is a ubiquitous part of daily life for a reason: IT WORKS.
And it works for different reasons: coupons and timed discounts or promotional offers provide an incentive to order that pizza or get that haircut this week rather than holding off. Special events provide a reason to go to a location or venue that otherwise would be ignored. And best of all, unique Direct Mail can stand out in a person's mind and make them think of a product or service at opportune (for both consumer and producer) moments.
Once I got a cocktail stirrer in the mail from Maker's Mark. I'll never forget it, and when I see red cocktail stirrers my mind instantly goes to that brand of bourbon. Once I did a DM campaign for a pachinko (think pinball meets slot machine) parlor in Tokyo that involved sending packets of soybeans for good luck (it's complicated if you don't know Shinto about Shintoism) to a myriad of local addresses.
The lesson in all this? Direct Mail annoys people and gets a bad name, but it works, and if done with a little creativity rather than the cut-and-paste method, it can work wonders.