Thank you for reaching out to Constant Contact API Developer Support. My team is here to assist outside software developers with questions about building into Constant Contact's API.
It is currently not possible to generate unsubscribe URLs outside of the predefined links in the footers of Constant Contact campaigns, however, this is something our engineering team has been looking into. I’ve added your account to a relevant feature request for this functionality. We appreciate you reaching out with this use case.
Please let us know if you have any other questions!
... View more