As part of a regular promotional email, you can include a Sonar link to a page that highlights the specifics of the promotion. If you include a tag as a part of that Sonar link, whenever someone clicks that link their metadata will change. This change will alert the Contact Changed element to start a workflow and send an email with a personalized promotional offer to whoever clicked the link.
When you are creating your promotional communication, make sure that you have ascribed a specific tag to the Sonar link that people will be clicking on. If you do not do this, there will be no metadata change when a user clicks on a link, and the Contact Changed element will not activate.
The Filter Duplicate element will ensure that anyone who has already received a personalized email will not receive another one if they happen to click the link again. This is done to prevent people from repeatedly accessing the promotion. If no such rules apply to your promotion, this step can be skipped.
Anyone who has clicked on your Sonar link will receive a personalized email detailing what they need to do to take advantage of your offer. By onboarding customers in this way, you can build a stronger relationship with them than if you were to simply supply a promotional code through one of your pre-existing channels.