Constant Contact is an email marketing platform that supports DMARC compliance through DKIM alignment for its customers. We've created a guide to provide you with all of the necessary steps and considerations for configuring Constant Contact: https://dmarcian.com/source-guide-constant-contact/
See our guide to configure DKIM.
Constant Contact does not currently support using the customer’s domain in a way that achieves SPF alignment. This means it will not pass DMARC with SPF.