To authorize Ipreo to send emails on your behalf you will have to add it to your SPF record. The SPF record mechanism used by Ipreo is shown below.
Ipreo support custom DKIM signing for customer domains. Please reach out to Ipreo support team for them to enable DKIM and provide you with the necessary DKIM records for your domain.
Create a free OnDMARC account to test your configuration.