Kayako runs on top of SendGrid which supports full DMARC compliance.
For DKIM configuration, please visit: https://help.kayako.com/hc/en-us/articles/360006457279-Protecting-Your-Emails-from-Spam-Filters
Add 'include:email1.kayako.com' to your SPF record. For more information, please visit: https://help.kayako.com/hc/en-us/articles/360006457279-Protecting-Your-Emails-from-Spam-Filters