I’m cun he, maker of InlinerAPI. If you maintain receipts, reset messages or invitations, I’d appreciate a current-work comparison: Check Email Content, Links and Required Sections · Inliner API

Use synthetic final rendered HTML and one independently expected copy, displayed-value or CTA-destination rule. The browser preview needs no signup. It checks supplied HTML; it does not run your templates, validate tokens or payments, or test delivery or inbox appearance.

What rule did you attempt and what result did you observe? Including setup, false positives and rule maintenance, does it add value beyond your existing tests? If useful for recurring business work, what would make these current checks worth paying for?