Unless your nonprofit wants to waste money printing extra direct mail pieces, and deal with complaints from people who received several copies of the same mailing, you should take time to become familiar with the “merge/purge” process.

When combining data from multiple sources, duplicate records can appear and need to be eliminated. The goal of a merge/purge is to produce one unique record that contains all of the valuable data but eliminates redundancy. This is especially critical when a business or association is attempting to create a large mailing list for their direct mail campaigns.

Many times, duplicate records contain bits of important information, and each record has a unique piece of information that should be saved. For example, duplicate customer records may contain the same name and address, but one record includes the customer’s email address while the other record includes the customer’s phone number.

Advanced data-matching techniques used in the merge/purge process generate one record that retains all of the valuable pieces of data and removes the duplicated data.


Name Address City, Zip Phone E-mail
Rec #1 123 Main St   Atlanta, GA 30348
Rec #2

123 Main St  

Atlanta, GA 30348 404-555-1212   
Rec #3

123 Main St,   Suite 4

Atlanta, GA 30348-9001
Best Rec

123 Main St.
Suite 4

Atlanta, GA 30348-9001 404-555-1212









Outlined below is a basic six-step merge/purge process that will create the best possible list of names for your nonprofit organization’s mailing by filtering out unwanted and duplicate entries — keeping you from pinching potential profits with wasted postage. 

1. List conversion

Before the merge/purge can begin, all files need to be in the same format. It’s nearly impossible to run a proper merge/purge if the data files vary in field length and layout. Garbage in, garbage out.

2. Pre-merge/purge count approval

Once you decide which lists you’re going to use, always approve your input quantities before starting the merge/purge. Make sure you received all the lists you ordered, confirm the quantities and double check that your list priorities are set correctly.

This simple, yet crucial, step might catch a mistake before the merge/purge runs — saving your nonprofit money and keeping your mailing on schedule. 

3. Address hygiene and standardization

The United States Postal Service’s National Change of Address database and various proprietary change-of-address databases will update addresses to the most current ones on file. Before mailing your next appeal, you need to run your list against the NCOA database. This is an important step to ensure you are going to reach the intended donor in a timely manner.

Standardization can fix misspelled addresses, names and abbreviations. Without the correct addresses, the matching and de-duplicating processes won’t do you any good. 

4. Merge/purge matching logic

  • Address only: Name fields are ignored; entries are matched based strictly on address.
  • Household: First names are ignored; entries are matched based on last name and address.
  • Individual: Nothing is ignored; all inputs must match.

You can apply the same matching logic across all data inputs or change it up by source, depending on your business rules. For example, you could suppress house-file matches at an address level, while simultaneously matching rental lists at a household level.

5. “Nthing”

The Nthing process extracts a sampling of names from a mailing list by applying selection criteria to end up with the desired quantity. This important process ensures a renter won’t be limited to names from one or part of the alphabet, or from certain zip codes. Some sample Nth select options are:

  • A/B split: The simplest split of lists (skip 1, take 1).
  • Random: Completely random select across all lists or a group of lists.

6. Final count approval

If everything went well, this is an easy step — and like the others above, it should never be skipped.

Many factors can complicate this basic breakdown of the merge/purge process. It’s not an exact science or automatic process, and it requires a balance of software and human judgment. But without it, even the most brilliant strategies, concepts and offers might never reach the mailboxes that would make your campaign a winner.