Email not working for payment gateway

Good day

I’m having issues receiving emails from my payment gateway, they are not coming in. I receive emails for clients that have registered and emails from my website. But when an individual places an order it redirects to a payment gateway. When an individual confirms or cancels the order the payment gateway redirects them back to my website, sending me an email notifying me of the above but I never receive the email. I don’t know how to configure this. May I please get help regarding this issue. I was working before I started using Cloudflare.