Cornerstone OnDemand is capable of sending DMARC compliant email because they support custom SPF and DKIM configurations that achieve DMARC alignment. Cornerstone OnDemand is an Employee Recruitment Platform and is often used by Human Resources.
The link just below is a resource on how to configure this source to send DKIM-aligned email on your behalf. You will need to engage your Account Manager to complete these steps. https://csod-external.force.com/supportcentral/s/article/How-to-enable-DomainKeys-Identified-Mail-DKIM?language=en_US
We recommend opening a support ticket with your Account Manager to get help with setting up a custom SPF configuration.