An automation has exactly one trigger. Five are available. "Contact is added to a list" enrols a contact when they join, whether by signup form, import, API, or manual add, and accepts a custom criteria filter. "When a contact is edited" enrols a contact when their record changes and takes the same fields. "Date based Automation" fires from a date, either a date field on the contact profile (birthday, renewal) or one specific calendar date, with filters Is Today, Occurring before, and Occurred after, an optional days-before offset, and Exclude Year and Exclude Month switches that let a yearly date field match every year. "When a contact opens an email" and "When a contact clicks on a link" enrol contacts based on engagement with chosen broadcasts, both requiring the source broadcast to have tracking enabled, and both taking an expiry duration after which the automation stops accepting new enrolments; the click trigger additionally lets you match any link or only specific URLs. All triggers accept Subscribers Custom Criteria to narrow enrolment by custom field values. Changing the trigger of a live automation does not retrospectively enrol contacts.
