Resend integration

Overview

Resend is a developer-first transactional email API – modern SDK surface, React-based templating, and a clean dashboard. The Automize connector covers send (single, batch), broadcasts, audiences, contacts, domains, and email management (get / update / cancel scheduled).

• Regions: Single global API at api.resend.com. Sending IPs are US-based; EU residency is on the roadmap but not yet GA.
• Plans: Free tier: 100 emails/day, 3000/month, sending domain limited to a Resend test domain (onboarding@resend.dev). Paid plans unlock custom domains, broadcasts, audiences, dedicated IPs.

Setting up the connection

Auth type: Bearer Token.

1. In Resend → API Keys, click Create API Key. Pick permissions: 'Full access' (sending + management) or 'Sending access' (send-only, no domain/contact CRUD).
2. Copy the key (re_...) – shown once. Paste as the API token. Connector sends Authorization: Bearer <key>.
3. For production, verify a sending domain (Domains → Add) – adds SPF/DKIM TXT records to your DNS. Onboarding can take 5-30 min for DNS propagation.

Find your credentials at https://resend.com/api-keys.

Rate limits

10 req/sec by default; raised on request for high-volume senders. Batch send (up to 100 emails / call) doesn't count against the per-second cap individually. 429 returns Retry-After; connector backs off.

Data model

Resend's sending graph splits transactional from broadcast:

    Account
      ├─ Domains             (verified via SPF + DKIM + MX)
      │    └─ Region         (us-east-1 default)
      ├─ Emails              (transactional sends, individually addressed)
      │    └─ scheduled_at?  (future-dated, cancellable)
      ├─ Audiences           (lists for broadcasts)
      │    └─ Contacts
      └─ Broadcasts          (one-to-many marketing, scheduled or immediate)

ID prefixes:

    email_id          UUID prefix-free; returned on Send + visible in webhooks
    audience_id       UUID for a list
    contact_id        UUID for a member of an audience (scoped per audience)
    broadcast_id      UUID for a staged or sent broadcast
    domain_id         UUID for a sending domain

Status flow for emails:

    queued → sent → delivered → opened? → clicked?
                              ↘ bounced (hard|soft)
                              ↘ complained (recipient marked spam)

All five terminal events fire as webhooks if configured. Suppression
is automatic on hard bounce + complaint – no API surface to remove.

Available operations

17 operations available. Click any row to jump to its detail.

Operations

Cancel Scheduled Email

Cancel an email scheduled for future delivery

Tips

• Only cancels scheduled (future) emails. Already-sent emails can't be unsent – Resend has no recall feature.

Create Audience

Create a new audience

Tips

• Audience is a contact list. After create, add contacts via Create Contact with audience_id.

Create Broadcast

Create a broadcast email campaign

Tips

• Broadcast = one-time blast to an audience (list of contacts). audience_id + from + subject + html/text.
• Send Broadcast triggers the actual send. Create Broadcast just stages it.

Create Contact

Add a contact to an audience

Tips

• email + audience_id + (optional) first_name, last_name, unsubscribed. Duplicate email in the same audience returns 409 – wrap with a check or accept and ignore.

Create Domain

Add a sending domain

Tips

• name=yourcompany.com + region=us-east-1 (default). Returns SPF + DKIM TXT records – add to your DNS and call Verify Domain.
• Custom-return-path subdomain (e.g. bounce.yourcompany.com) is set up automatically for paid plans.

Delete Audience

Delete an audience

Tips

• DELETE /audiences/{audience_id} – removes the list and orphans its contacts (contacts persist account-wide for billing/reconciliation).
• Doesn't cancel any pending broadcasts that reference this audience – those return 'audience not found' at send time.

Delete Contact

Delete a contact from an audience

Tips

• DELETE /audiences/{audience_id}/contacts/{id_or_email} – removes the contact from this audience only. Same email in another audience is unaffected.
• GDPR erasure: delete from every audience + suppress for future sends. Resend doesn't expose an account-wide 'forget user' yet – track erasure on your side.

Get Email

Get a single email by id

Tips

• GET /emails/{email_id} – returns the original send payload + last_event (queued|sent|delivered|bounced|complained|opened|clicked).
• Useful for status look-ups when you didn't subscribe to webhooks. Retained ~7 days; older emails return 404.

List Audiences

List all audiences

No input parameters.

Tips

• Returns marketing lists. Each audience has a contact_count snapshot – refresh by re-listing if you've added contacts.

List Broadcasts

List all broadcasts

No input parameters.

Tips

• Staged + sent broadcasts. status: draft → queued → sent → (failed). Includes sent_at + audience_id for each.

List Contacts

List contacts in an audience

Tips

• Per-audience listing. GET /audiences/{audience_id}/contacts. Unsubscribed contacts are included unless you filter client-side by unsubscribed=false.

List Domains

List verified sending domains

No input parameters.

Tips

• GET /domains – every sending domain on the account + verification status per record (SPF, DKIM, MX, DMARC, return_path).
• Status: not_started → pending → verified → failed. Region (us-east-1, etc.) is per-domain.

Send Batch

Send up to 100 emails in one call

No input parameters.

Tips

• Up to 100 emails / call. Each entry is a full Send Email payload (from, to, subject, html/text).
• Returns an array of email_ids – same order as input. Each email is independent: one failure doesn't abort the rest.

Send Broadcast

Send (or schedule) a broadcast

Tips

• POST /broadcasts/{broadcast_id}/send – fires the actual send to the audience. scheduled_at (ISO 8601) future-dates it.
• Idempotent in the sense that sending an already-sent broadcast 409s – Resend won't re-blast the same broadcast.

Send Email

Send a single email

Tips

• Required: from (verified domain or @resend.dev), to (string or array), subject, plus html OR text.
• react=<React component> works in the official SDK but Resend's REST surface accepts pre-rendered HTML only – render on your side and pass html.
• scheduled_at: ISO 8601 timestamp to schedule send. Returns email_id; cancellable via Cancel Email up to the scheduled time.
• tags=[{name,value}] surface in webhooks + the dashboard. Use them for routing analytics downstream.

Errors

• 403 – Sender domain not verified, or you're sending to a recipient outside your verified domain on the test (onboarding@resend.dev) sender. Verify the domain or send to your own address.
• 422 – Missing required field (from / to / subject / body).

Update Scheduled Email

Update a scheduled email's send time

Tips

• Only valid for scheduled (future) emails. PATCH the scheduled_at to reschedule, or change html/text/subject before send.
• Once an email's status flips past 'queued', updates 400.

Verify Domain

Trigger DNS verification on a domain

Tips

• Triggers Resend's DNS check. Returns status='not_started' | 'pending' | 'verified' | 'failed'. Verification is per-record (SPF/DKIM/DMARC), so a partial pass is possible.

FAQ

Sending domain – really need it?

For production yes. Resend's test domain (onboarding@resend.dev) only sends to your own verified email – useful for ad-hoc tests, blocked for real recipients. Verify a custom domain before any user-facing send.

React Email templating – do I render server-side or send the JSX?

Render server-side. The official SDK does this for you via the react: prop. Over REST, you pass pre-rendered html. Either way the API never sees the JSX.

Bounces and complaints – auto-suppress?

Hard bounces and spam complaints add the recipient to the suppression list automatically. List via the dashboard (no API surface for suppressions yet).

Broadcasts vs Send Email loop – when is each right?

Broadcasts: announcements/newsletters to an existing audience (1 → N). Send Email / Batch: per-user transactional (signup welcome, password reset). Don't loop Send Email for a 10k blast – use Broadcast.

Webhooks?

Resend webhooks fire on send/delivered/bounced/complained/opened/clicked. Configure under Webhooks → Add endpoint. Verify signatures via Svix-style HMAC – the secret is shown on creation.

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