Custom fields allow you to insert content into newsletters.  In version 9, we added support for specifying unlimited variations of a custom fields that can be embedded in the newsletter based on the 25 subscriber demographic fields.

For example, if you have a demographic field called Gender and wish to insert a unique image for Male versus Female, here is an example:

Let's say you wanted to insert specific content for those age 30 and younger versus those over 30.  Here is another example:

The Evaluation Order allows you to control the order in which each demographic fields is evaluated. Once a match is found that dynamic custom field HTML or TEXT is inserted into the newsletter.