Isn’t this what DMARC is for? I have this setup (along with SPF) with my domain with a strict “reject” policy and a dedicated inbox to receive delivery reports.
I do like that you are tracking whether the recipient opened the email or not. But most email clients are no longer loading images (including the “tracking pixel”) by default so this nice feature/metric can be misleading.
> More recently, as a VP of Developer Experience at WorkOS, I once again had to deal with emails landing in the spam folder
This usually means DMARC is configured incorrectly or just too many of your recipients are marking the emails as spam.
Besides the ability to write templates using react syntax, I don’t see why developers would use yet another centralized service in production.