Double opt-in mailing list signup with Caldera Forms CiviCRM
You can use Jaap Jansmas integration of CiviCRM with the Form Processor for that: Just create a form processor using the action &quot;Mailing Event: Subscribe to mailing list&quot;. You can even create simple deduplicating rules using conditions on the actions &quot;Contact: Get Individual by name and email&quot; and &quot;Contact: Create or update Individual&quot;. The form processor will then appear as a Caldera Forms processor and you just add your slugs. Never forget to clear the CiviMcRestFace Log in Settings CiviCRM McRestFace Call Log when adding/changing form processors.
Update: Now Jaaps plugin can also be installed from the official Wordpress plugin repo:
https://wordpress.org/plugins/cf-civicrm-formprocessor/