By Jeffery Dobkin, marketing consultant, author, and professional speaker

1. Ask the origin of the list. 
There are two types of lists, determined by their origin: compiled lists and response lists.
Compiled lists are a common source of names and records that have been gathered, collected, and entered into a database. The names may have been acquired through public records such as vehicle owner registrations, or through directories such as phone books from each city across the U.S. Examples of compiled lists are all the photography shops, or all the luggage dealers in the United States. Directories, such as a directory of plant maintenance engineers, are usually compiled lists. 
Response lists are names and addresses of people or firms who have responded to a magazine ad, or who have purchased from a catalog, direct mail package, TV ad, or other offer. List with respondents are better bets when selling general lines of merchandise.
2. Precisely who is the list comprised up of? 
With any mailing you are considering, first ask exactly what groups or what characteristics make up the perfect target audience for your offer. Then try to find a list that closely matches these definable characteristics.

3. Does the list include actual purchasers or merely inquirers? 
Purchasers are much more valuable than inquirers – anybody with a pencil can inquire; purchasers have proven they have money to spend and aren’t afraid to put it in the mail when they see an offer they like. This key question separates the spenders from the rest.
4. How old are the names on the list? 
Like fish, names go bad rather quickly when left out on the table for any length of time. The more recent the data records, the more likely you’ll have a greater percentage of response. The list is the last piece of the direct mail puzzle to buy – research it well, and ensure the freshest names actually make the purchase right before your mailing.
5. How often – and how recently – has the list been cleaned? 
Cleaning a list means running it through the National Change Of Address (NCOALink®) file of the Postal Service™ – and removing the non-deliverable names or “nixies.” You’ll get less mail back if the list has been cleaned recently.
6. How recently have the people on the list made a purchase? 
A person who has just made a purchase through the mail is MOST LIKELY to immediately purchase again. Recency of purchase is one of the key issues in the purchase of a list. Some list houses offer “Hot Name” selects: a file of just their latest name acquisitions. Test this list segment first – if it mails profitably, you can go back and order the rest of the file. Beware: different companies have different time requirements on their hot name files. Some companies have a hot file of one-month-old names, another company’s hot file may be six-month-old names. So ask.
7. Can you get a “Select” of multi-buyers – and how frequently they’ve purchased?
Some of the larger list houses will run a program to find names that appear on several response lists, and offer these as a selection you can mail to. These are proven mail order buyers and are more likely to purchase again through the mail. They’re my favorite, and I recommend this option if it’s available.
8. How often has the list been rented? 
You want to rent a list that gets some use, but not a list that is rented too much. If it never gets rented, there is usually a reason – it doesn’t work. Most list houses will recommend a list to other mailers if it’s working. However, you don’t want to buy a list that is fatigued – you don’t want to be the 30th pet products catalog the pet owner receives that month.
9. How many other mailers have tested the list? 
Look for a list that has been tested enough so that you can get a read-out of its activity. Mailers rent 5,000 names to test if that segment of the population is profitable for their offer. Ask how many others have recently rented the list for a test.

10. How many people continued after their test?
Probably the second BEST way to tell if a list is working: mailers mail to it once, find that it’s profitable, and come back and purchase more names. A good rule of thumb: if you mail to a list and it’s profitable, you can mail up to ten times the names of your last mailing. If you rent 5,000 names and it’s profitable, you can now go back and mail up to 50,000 names. If that tests successfully, go back and rent up to 500,000 names. If that tests successfully, call me and we’ll talk.

11. How many people rolled out to the rest of the list?
Dramatic success in a mailing list shows up if the tests are successful and the mailer eventually winds up mailing to the entire list. This is the BEST way to tell if a list is working.
12. Ask if you can get a free sample of 2,000 names to test.
You never know unless you ask. You may be able to test your mailing without paying for a list. Some list owners know their list works well, and if it works for you, you’ll be back for more names. Don’t forget to ask.
—Source: Jeffrey Dobkin is a copywriter, a speaker, and direct marketing consultant. He is also a Favorite Author of Melissa Data’s Direct Marketing Advisor. Read his most recent article here and call for his free instructional booklet of direct marketing tips: 610/642-1000 or visit his Web site at www.dobkin.com