Is DMARC record really as simple as it sounds?

Thank you for sharing this. Glad to see that in your tests that everything seems to be passing when you check the headers. Mailbox providers check the SPF record against the Return-Path domain, not the sending IP. However, if it’s important for you that the reports are showing a pass (will not have any impact to your actual email deliverability), you may be able to achieve that by added include:sendgrid.net (instead of include:mailer.shopify.com). Let me know if that works!