osTicket 1.9 introduces a new feature: custom properties for list items. This feature is supported in osTicky 2.2 and ticket/message alerts and auto-responses sent by osTicky will fill related email templates with the property values, if the template makes reference to these properties. osTicket documentation doesn't explain clearly how to reference list items properties in email templates, so it's worth mentioning it here.

Suppose the you have added a custom list field to your ticket form (optionally assigned to a specific help topic). Take note of the list "plural name". Then go to "Properties" tab in the list configuration. Add one ore more properties and take note of each property "Variable" value. The template variable to be added to the desired email template(s) should look as: %{ticket.list_plural_name.property_variable}