SendSignal documentation

SendSignal is a developer email API: transactional sends, marketing broadcasts, automations, audiences, and inbound parsing behind one REST surface, powered by Amazon SES.

Before going to production you’ll want to:

1. Verify a domain so your mail authenticates with DKIM and SPF.
2. Create an API key in the console under Platform → API Keys.

Quickstart

Get an API key and send your first email in a few minutes with plain HTTP.

Start sending →

API reference

The full interactive reference, generated from the OpenAPI spec the API serves at /openapi.yaml.

api.sendsignal.dev/docs →

Send

Send emailsPOST /emails, plus batching, attachments, scheduling, and idempotency keys.

Message streamsSeparate transactional and broadcast traffic, with different unsubscribe semantics.

TemplatesVersioned templates with aliases, variables, and a draft → published flow.

SMTP relayPoint anything that speaks SMTP at SendSignal; the password is your API key.

Grow

Broadcasts & audiencesContacts, segments, and topics; one-to-many sends that respect opt-outs.

AutomationsEvent-triggered sequences: welcome series, follow-ups, auto-replies.

Operate

DomainsVerification, tracking, DMARC with hosted reports, BIMI, and inbound email.

WebhooksSigned delivery events, retries over days, replay, and a live SSE stream.

Email statsSend and engagement time series, filterable by stream, domain, or tag.

Errors, rate limits & paginationThe practical API mechanics before you ship.

Free email tools

tools.sendsignal.dev has free DNS, SPF, DKIM, DMARC, BIMI, blocklist, and header-analysis tools, useful whether or not you send with us. And for AI agents, there’s an MCP server plus SDKs on the way.