Mosaico mail template URL's don't function properly
Paul, welcome to CiviCRM stackechange. when you have clickthrough enabled for the mailing CiviCRM replaces those url into trackable url so that Civi can track clicks for mailing. Check you Resource url setting (Administer >> System Settings >> Resource url .. click on '?' under the help area), Make sure [civicrm.path] is set correctly. Try sending the same email by replacing the path for CiviCRM resource url field.