resend

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Resend email API for sending transactional and marketing emails. Use when integrating email delivery, managing domains, handling webhooks, building email workflows with React Email, managing contacts, or sending broadcasts. Use for resend, email, transactional, broadcast, contacts, segments, webhooks, domain.

1installs

Sourceoakoss/agent-skills

Added on2026-02-24

NPX Install

npx skill4agent add oakoss/agent-skills resend

SKILL.md Content

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Resend

Overview

Resend is a modern email API built for developers, providing programmatic email sending with support for React Email components, domain management, and webhook-driven event tracking.

When to use: Transactional emails (welcome, password reset, receipts), batch email delivery, scheduled sending, webhook-based delivery tracking, domain verification, React Email integration.

When NOT to use: High-volume marketing automation (use dedicated ESP), SMS/push notifications, email hosting/inbox management.

Quick Reference

Pattern	API	Key Points
Send email	`resend.emails.send({ from, to, subject })`	Returns `{ data, error }` , supports html/text/react content
Send with React	`resend.emails.send({ react: <Email /> })`	Node.js SDK only, renders React Email components server-side
Batch send	`resend.batch.send([...emails])`	Multiple emails in one request, no attachments/scheduling
Schedule email	`emails.send({ scheduled_at })`	ISO 8601 or natural language, cancel before send window
Attachments	`emails.send({ attachments: [...] })`	Max 40MB total after encoding, supports content or path
Idempotent send	`emails.send(params, { idempotencyKey })`	Prevents duplicate sends on retry
Retrieve email	`resend.emails.get(emailId)`	Check delivery status and metadata
Add domain	`resend.domains.create({ name })`	Returns DNS records for SPF, DKIM, MX
Verify domain	`resend.domains.verify(domainId)`	Triggers DNS record check
List domains	`resend.domains.list()`	Returns all domains with status
Create webhook	Dashboard or API	Subscribe to email lifecycle events
Verify webhook	`resend.webhooks.verify({ payload, ... })`	Validates Svix signature headers
Tags	`emails.send({ tags: [...] })`	Key-value pairs for categorization, ASCII only, max 256 chars
Custom headers	`emails.send({ headers: {...} })`	Add custom email headers
Create contact	`resend.contacts.create({ email, ... })`	Global contacts with custom properties
List contacts	`resend.contacts.list()`	Returns all contacts
Create broadcast	`resend.broadcasts.create({ from, ... })`	Bulk email to a segment, supports template variables
Send broadcast	`resend.broadcasts.send(id, { segmentId })`	Delivers broadcast to a segment of contacts

Common Mistakes

Mistake	Correct Pattern
Using root domain for sending	Use a subdomain like `send.yourdomain.com` to isolate reputation
Not checking `error` in response	Always destructure `{ data, error }` and handle errors
Sending attachments in batch requests	Attachments and scheduling are not supported in batch sends
Hardcoding API key in source code	Use environment variable `RESEND_API_KEY`
Skipping webhook signature verification	Always verify using Svix headers before processing events
Using `react` prop outside Node.js SDK	The `react` prop only works with the Node.js SDK
Not setting up DMARC after SPF/DKIM verify	Add DMARC record after SPF and DKIM pass to improve deliverability
Exceeding 50 recipients in a single send	Use batch send or loop for more than 50 recipients per request
Using `&&` for tag name/value characters	Tag names and values must be ASCII letters, numbers, `_` , or `-`
Ignoring bounce/complaint webhooks	Monitor `email.bounced` and `email.complained` to protect reputation

Delegation

Email template design: Use
```
Explore
```
agent to discover React Email component patterns
Domain DNS configuration: Use
```
Task
```
agent for step-by-step DNS setup verification
Webhook endpoint setup: Use
```
Task
```
agent for route handler implementation

References

Sending emails, batch sending, attachments, scheduling, and idempotency
Contacts, Segments, Broadcasts, template variables, and bulk sending
Domain verification, DNS records, and sender identity management
Webhook events, signature verification, and event handling