In the direct mail game, you're only as good as your list. Direct marketing is expensive. It costs a lot less to reach 10,000 people through the newspaper than through the mail. More than any other form of advertising, direct mail rewards smart marketing. Direct mail is about paying more to choose your eyeballs.
Mailing lists are a valuable byproduct of most business ventures.
All the lists can be useful. Mailing list brokers can break up lists by zip code, but you can get even more specific information by using census tracts-areas of a few blocks or a few acres with about 4,000 or so people. Census tract information includes hundreds of demographic variables about each census tract. Usually, the more tightly targeted your mailing, the more you will have to pay for your list. The expense of adding a few extra levels of selectivity is usually worth it.