The Email service sends transactional email — sign-up confirmations, password resets, receipts, security alerts — through a small JSON-over-HTTPS API.
You authenticate with an API key, POST a payload, and track every message through delivery webhooks and the dashboard.
Looking for plans or pricing?
Sending volumes, the free tier and pricing are not documented here — they live on the transactional email service page. This section covers the API and how sending works.
Transactional only
Section titled “Transactional only”Runsite Email is built and tuned for one recipient (or a few) at a time, triggered by something a user did inside your app. It is not a bulk-email or marketing platform.
| Allowed | Not allowed |
|---|---|
| Sign-up & verification emails | Newsletters and promotional blasts |
| Password resets, magic links, MFA codes | Mass marketing campaigns |
| Receipts, invoices, payment confirmations | Bulk announcements to lists you bought, scraped or imported |
| Order, shipping and account-status notifications | Cold outreach, sales prospecting |
| Per-user system alerts (security, errors, mentions) | Anything sent to recipients who didn’t explicitly request your product |
Hard limit: up to 50 recipients per request across to, cc and bcc combined. There is no broadcast / list / segment functionality.
What you get
Section titled “What you get”- A dashboard in your workspace to create email services, manage sending domains, generate API keys, configure webhooks and watch delivery stats.
- A public REST endpoint at
https://api.runsite.app/emailsthat any backend (or HTTP client) can call directly. - Bring your own domain — verify with SPF + DKIM + DMARC and send from any address on your domain (
hello@yourdomain.com,noreply@app.example.com, …). - Sandbox mode for safe development — a shared sender address that delivers only to recipients you explicitly verify.
- Webhooks for delivery / bounce / complaint events with HMAC-signed payloads.
Concepts
Section titled “Concepts”| Email service | A logical sender, scoped to your workspace. You can have several — one per app, one per environment (dev / staging / prod). Each service has its own API keys, domains, sandbox settings and stats. |
| Sending domain | A domain you own that has been verified (DNS records) for sending email. |
| API key | The credential clients send in the Api-Key: header to authenticate. Looks like rs_eml_…. |
| Sandbox mode | A safety mode every new service starts in. Delivers only to recipients you’ve explicitly verified, so you can build and test without spamming real users. |
| Production mode | Unlocked once you have at least one verified sending domain. Lets you send From: your domain to anyone. |
| Webhook | Your HTTPS endpoint that Runsite POSTs delivery events to. Each call is HMAC-signed. |
Sandbox vs production at a glance
Section titled “Sandbox vs production at a glance”| Sandbox mode | Production mode | |
|---|---|---|
| Default for new services | ✅ | — |
| Need a verified domain? | ❌ | ✅ |
| Who can receive? | Only recipients you explicitly verified inside the service | Anyone |
From: address | Shared sandbox sender (onboarding@runsite.app) | Any address on your verified domain |
| Daily limit | Low — meant for development | Per-service quota that grows with reputation |
Endpoint
Section titled “Endpoint”There is one public endpoint for sending email:
POST https://api.runsite.app/emailsApi-Key: rs_eml_…Content-Type: application/jsonEverything else (creating services, adding domains, managing keys, configuring webhooks, viewing stats) lives behind the dashboard.
Can I send marketing emails or newsletters through Runsite Email?
Section titled “Can I send marketing emails or newsletters through Runsite Email?”No. Runsite Email is for transactional traffic only — messages triggered by a user’s action, like sign-up confirmations, password resets and receipts. For newsletters and campaigns, use a dedicated marketing platform.
What’s the difference between sandbox and production mode?
Section titled “What’s the difference between sandbox and production mode?”Sandbox mode is the default for new services and delivers only to recipients you’ve explicitly verified, so you can test without spamming real users. Production mode unlocks once you have a verified sending domain and lets you send to anyone. See Sandbox mode.
How many recipients can one request have?
Section titled “How many recipients can one request have?”Up to 50, counted across to, cc and bcc combined. There’s no broadcast, list or segment functionality.
How do I send from my own domain?
Section titled “How do I send from my own domain?”Verify a domain you own with SPF, DKIM and DMARC records, then send from any address on it. See Sending domains.
How do I track whether an email was delivered?
Section titled “How do I track whether an email was delivered?”Configure a webhook to receive delivery, bounce and complaint events — each call is HMAC-signed — or watch delivery stats in the dashboard. See Webhooks.
Where to next
Section titled “Where to next”- Dashboard — every tab on an email service.
- Sending domains — verify your domain with SPF / DKIM / DMARC.
- Sandbox mode — test without spamming, then go to production.
- API keys — issuing, scoping, rotating credentials.
- Sending emails — endpoint, payload, full code examples.
- Webhooks — delivery events and signature verification.
Need to send marketing or bulk email?
Runsite Email is for transactional traffic only. For newsletters, drip campaigns and segmented marketing use a dedicated marketing platform — they handle list management, unsubscribe, deliverability and reporting that bulk email needs.