Our data indicates DigitalInsight is DMARC compliant via SPF.
Contact DigitalInsight to ask about their DKIM capabilities.
DigitalInsight provide 'include:spf.digitalinsight.com' as an addition for your SPF, however that pulls in a lot more than you need. Instead of adding unnecessary authorizations to your SPF, you could contact DigitalInsight to understand if there's a more strict addition for your record.