WPEngine is a web hosting platform that focuses on WordPress. Their solution comes with an integrated email component that functions on the MailChannels infrastructure.
At the moment WPEngine's built in email solution does not support DMARC Alignment.
Our recommendation for customers who wish to send from WordPress as their domain, is to leverage one of the many plugins available in the WordPress repository. WPEngine also recommend using a third-party host instead of the default service.
"WP Mail SMTP" from WPForms, is one of the plugins preferred by many customers. For the SMTP relay the options are to use your corporate infrastructure to send emails, or a 3rd party transactional service (check the Recommended Email Hosts here). The latter may come with additional costs depending on the volume of emails that you send from WordPress.
If you choose to configure the SMTP plugin with a 3rd party transactional service, there are additional steps necessary to set up SPF and DKIM. Go to the Sender Authentication for Specific Services section in our knowledge base and look for the instructions to set up the service in Valimail Authenticate.