Quickstart: send your first email

This guide takes you from a fresh SendBunny install to a delivered transactional email. Every step is explicit — no context is assumed beyond the prerequisites listed below.

Prerequisites

A SendBunny install in your AWS account. SendBunny is self-hosted: there is no shared SaaS endpoint. If you have not installed it yet, see Deploy — installation is a pre-filled CloudFormation template and takes about 10 minutes.
Admin access to your SendBunny dashboard. The install emails the first admin a temporary password. API keys can only be created by users in the ADMIN role.
A verified sender domain. In the dashboard, open your domain's onboarding page and complete DNS setup (DKIM/SPF/DMARC records). The API refuses to send from unverified addresses with HTTP 403.
SES production access (for real recipients). New AWS accounts start in the SES sandbox, which only delivers to verified recipient addresses. The dashboard includes a wizard for requesting production access. In the sandbox, sends to unverified recipients fail with HTTP 502.

Step 1 — Create an API key

In your SendBunny dashboard, go to API Keys (left sidebar).
Click New key, name it, and select the sending domain(s) the key may use. A key can only send from the root domains it was issued for.
Copy the key immediately. It starts with sb_ and is shown exactly once — SendBunny stores only a hash. If you lose it, revoke it and create a new one.

Because SendBunny runs in your own AWS account, your API endpoint is unique to your install. The same API Keys page in the dashboard shows your Transactional API URL — an AWS Lambda function URL that looks like https://abc123xyz.lambda-url.us-east-1.on.aws/. All requests are a POST to that URL.

Step 3 — Send an email

Replace the URL, the key, and from (must be an address on a domain you verified — see prerequisites — and allowed for this key in Step 1). In the SES sandbox, to must be a verified recipient or an SES mailbox simulator address like success@simulator.amazonses.com.

curl

curl -X POST 'https://YOUR-INSTALL.lambda-url.us-east-1.on.aws/' \
  -H 'Authorization: Bearer sb_YOUR_KEY_HERE' \
  -H 'Content-Type: application/json' \
  -d '{
    "from": "hello@yourdomain.com",
    "to": "success@simulator.amazonses.com",
    "subject": "Hello from SendBunny",
    "html": "<p>It works!</p>"
  }'

A successful send returns HTTP 200 with the SES message id:

Response

{ "messageId": "0100018f2ab4c123-..." }

Troubleshooting

Status	Error	Fix
401	`Unauthorized` / `Invalid API key`	Send the key as `Authorization: Bearer sb_...`. Check the key was not revoked.
403	`This API key is not allowed to send from that domain`	The `from` domain is not in this key's allowed domains. The response lists `allowedRootDomains`; use one of those or issue a new key.
403	`From address is not a verified sender identity`	Complete domain verification in the dashboard for the `from` domain (DNS records must be live).
400	`'subject' is required` and similar	Field validation failed — the error message names the exact field. See the API reference for the full request contract.
422	`Recipient is on the suppression list`	The recipient previously bounced, complained, or was manually suppressed. Remove them in dashboard → Suppression only if you are certain the address is deliverable.
502	SES error message	SES rejected the send — most often sandbox mode (unverified recipient) or sending-quota limits. The message is passed through from SES.

Next steps

Full API reference — every field, every error, rate behavior.
Email templates — store templates in the dashboard, send with templateAlias + data merge variables instead of inline HTML.
OpenAPI spec — machine-readable contract for codegen and AI agents.