Sending API, SMTP & developer experience
How this is scored
How an application sends mail: a REST API and an SMTP relay with their limits stated, official SDKs and drivers for named languages and frameworks (PHP and Laravel, Node, Python, Ruby and Rails, Java, Go, .NET), stored templates with variables and versions, batch sending, attachments, idempotency keys, scheduled sending, a test or sandbox mode that does not deliver, inbound email parsed into a webhook, and the quality of the API reference and guides.
0 — Not a sending service; an application cannot send email through it by API or SMTP.
3 — An API or SMTP credentials to send a message; SDKs, templates, limits and a test mode are basic or not described.
5 — A documented REST API and SMTP relay, official SDKs for several named languages, stored templates with variables, attachments and batch sending, rate limits stated, a sandbox or test mode, and quick-start guides for named frameworks.
8 — An API reference with every endpoint and error code, idempotency keys, scheduled sending, template versions and a template language documented, inbound email parsed to a webhook, an OpenAPI specification or official CLI, framework drivers maintained by the vendor, and a migration guide from named competitors.
10 — An API a team builds its product on: versioning and deprecation policy published, backward compatibility stated, full parity between API and SMTP features, local or staging test tooling that mirrors production, and every limit, timeout and retry behaviour documented.
The SaaS Developer
The REST API and SMTP relay are both fully documented, with a PHP SDK named, a Laravel SMTP swap, Liquid templates with variables and conditionals, idempotency keys, a batch endpoint, scheduled sending and a sandbox that simulates deliveries, bounces and complaints before a real customer is emailed — nearly everything my password-reset pipeline needs. Inbound mail arrives parsed with SPF, DKIM and DMARC checks as an email.received webhook, and there is an official CLI and MCP server on top of the SDKs. It stops short of the top band because SMTP sends only the exact MIME your app submits and cannot render stored templates, so the two channels are not at parity, and we found no public information on an API versioning or deprecation policy. 1 2 3 5 6 14