Direct mail is a powerful medium. It brings ideas, propositions and brands into the sanctity of consumers' homes, usually, uninvited.
The key driving concept to direct mail is targeting–the idea that advertisers can identify specific groups of people and mail only them in their homes, and that the accuracy of this targeting determines the success of the mailing as determined by what-it-gained for what-it-cost, its ROI (Return On Investment).
Bizarly, given how valuable the platform, little attention is paid to the creative element and its impact on all those people who don't respond. Given that usual response rates are circa 2%, that means the feelings and sentiments of 98% of people go largely ignored.
The power of direct mail could hardly have been better tested than with this piece from DDB in Chile, who wanted to prove that condominiums could be easily accessed by theives as a way of selling security systems. I'm not how many people ran out and bought a burglar alarm in response to this, but you can bet a whole lot more felt invaded.