The Default Registration Link Tag works in conjunction with the Confirmation Link.
When a user clicks a Confirmation Link, if the default registration link tag is set then that tag will be applied to the user’s record in ActiveCampaign.
Ways to Use
The only function this feature provides is applying a tag when a confirmation link is clicked. This means you could easily use this tag to trigger another automation that only runs for “Verified” users since the only way they could get the tag is by clicking the link in their email thus confirming a valid email address.
Of course, there are many use cases and in some cases you may just want to apply a tag to have record they clicked the confirmation link.