Where to add SPF/DMARC/DKIM on RabbitMQ/MailerQ

First time setting up SMTP.
I got barebones working where I am able to send out emails but they land in spam. For this I need to add SPF/DMARC/DKIM. Where do I add them in RabbitMQ/MailerQ?

I was following this guide

Thank you.

You add SPF/DKIM/DMARC in DNS records.