Every application sends email: sign-ups, password links, invoices, notifications. Running your own mail server rarely makes sense – deliverability depends on IP reputation, DNS authentication and bounce handling, and every mistake ends up in your customers' spam folders. An email API takes care of that.
An API you already know
The ridu API is a plain REST interface with JSON. Sending an email is a single call:
curl -X POST https://api.ridu.ai/emails \
-H "Authorization: Bearer rd_live_…" \
-H "Content-Type: application/json" \
-H "Idempotency-Key: order-4711" \
-d '{"from":"Shop <hello@mail.shop.com>","to":"customer@example.com",
"subject":"Your order","html":"<p>Thanks!</p>"}'Because the API is compatible with Resend, you use the official SDKs for Node.js, Python, PHP or Go – no new dependency.
What the API does
- Idempotency: with an
Idempotency-Key, a repeated request within 24 hours creates no second email – essential for timeouts and retries. - Batches: up to 100 emails per call, all or nothing.
- Scheduling:
scheduled_atas timestamp or “in 2 hours”, reschedulable and cancelable. - Templates: versioned, with variables; values are HTML-escaped.
- Attachments: base64 or by URL, up to 40 MB in total.
- Webhooks:
email.delivered,email.bounced,email.complainedand more, signed and retried. - Test mode: test keys process everything but deliver nothing. Simulation addresses produce bounces and complaints.
GDPR without detours
The API runs on servers in Germany. The data processing agreement is concluded at signup. ridu deletes email content after seven days (down to “right after delivery”) and metadata after 30 days. Open and click tracking stays off until you deliberately turn it on.
Deliverability included
Every email is signed with your domain's DKIM key; SPF and DMARC alignment come from a single CNAME. ridu processes bounces and spam complaints automatically and suppresses affected addresses before they hurt your reputation.
The documentation lists every endpoint, error code and example.