Whenever you use Excel to create a mailing list make sure that you define the ZIP code field correctly, rather than having Excel automatically define field as a “number” field. If not, the leading zeroes drop off records.

If field isn’t correctly defined, zip code 00988 will become 988 and zip code 02222 becomes 2222. And none of your mail pieces whose zip codes begin with a 0 will be properly delivered.

To fix the problem:
In your Excel spreadsheet…
a. highlight the entire ZIP code column, including column description
b. click Format from commands at top of screen
c. click Cells
d. click Special
e. click Zip Code
f. click OK