Blog author chiming in:

Our initial blog covered most of Email Service's API and what you can expect from it in terms of deliverability, DNS records setup, etc. https://blog.cloudflare.com/email-service/

Email Service can definitely be used as a transactional email API, and it has everything you would expect like SDKs, binding, observability and more coming on the way

The agent angle in this post reflects what we're actually seeing from developers during our private beta. And the idea that an agent can have an inbox to communicate is a new piece in the developer toolbelt.