Restore Opencart Email Notifications

Since switching the store’s traffic to Cloudflare, OpenCart no longer sends order-related emails and, at the same time, refuses to save the new order status in the admin screen. My first priority is to get the customer and admin notifications flowing again... (Budget: $30 - $250 USD, Jobs: Cloudflare, DNS, Open Cart, SMTP, Troubleshooting, Web Development, Web Hosting)