https://api.signal.apollodeploy.com by default.
Before you start, create an API key with Emails: Send permission
and verify the From domain.
1
Install the SDK
2
Store your API key
Set
SIGNAL_API_KEY in your server environment. Never expose it to browser code.3
Send an email
to, cc, and bcc are arrays. Your from address must use a domain verified in the same Signal
project as the API key.Production use
- Reuse the client across requests.
- Add
idempotencyKeywhen a job may retry the same logical send. - Keep the key in a server-side secret manager.
- Use the returned ID or signed webhooks to follow delivery outcomes.
All SDKs
Compare every supported language and framework.
Manage emails
Understand message states and delivery timelines.