"Mail merges are a great way to save time, since they pull
information from the same fields, over and over again with each new
record in your database. There’s only one problem—all
records aren’t created equal; they don’t all have, or
all need, the same fields. This article solves that perpetual
problem with labels. If you’re already familiar with the
problem, you can go straight to the solution entitled: Suppressing
blank lines with sections step by step."