Engaged users should get a different treatment than the rest; they should get a more personalized experience which rewards their engagement an email at a time! Those who change the information in a specific custom field receive an email that is a tad more familiar and personal.
Any change in a specific custom field that occurs for the first time should activate a trigger and send personalized content. For example, if you have set a custom field to “State” and that changes from [null] to “Ontario”, then you can send a particular email campaign to the subscriber.
Use this automated workflow recipe to send the most appropriate email campaign to your subscribers, according to a custom field value indicating whether they are on the free plan or paying customers. The automation will be triggered the first time the field value changes, i.e. when the subscriber becomes a customer.