Zen Cart contains a table called
query_builder which contains queries that are used to build lists of email addresses for the Send Email and Newsletter Manager functions.
There is no admin panel interface to this table, but new audiences may be created by copying existing rows and updating as needed. For example, a list of all newsletter subscribers who have purchased in the last year could be made by copying “Active customers in past 3 months (Subscribers)” and adjusting the query_name, query_description and query_string values in the new row.
It can be helpful to turn on Audience-Select Count Display while doing this to see the size of the created lists.
You can also use plugins like Email Address Exporter to build email lists based on audiences.