A DMA study published in 2007 reported that 6.8 million pieces were mailed in the previous year, compared with an average 1.9 million emails.
The key is (always): list, offer, and creative.
If the list is no good (not relevant, not responsive, not clean) the whole thing falls apart, regardless of what medium you are using. Compiled lists (from telephone books, directories, or other passive sources) can be appealing when you’re starting out, because they’re cheap. However, they should be a list of last resort for a number of reasons. One, the people on those lists haven’t bought anything or responded to any offers. Two, the lists are not updated. Three, reasons one and two will cost you money and depress your response.
If the offer is no good or not relevant (sending a coupon for Depends to a list of college students), or too complicated, or hard to respond to, then response will go down.
If the creative (the copy and design) is unappealing, doesn’t catch readers’ attention, etc. then it goes in the wastebasket.
Personalization, “lumpy” mail (sending a USB drive for instance), multi-channel marketing, and a coordinated campaign (repeat mailings) can all help, but concentrate on the list, offer, and creative first.