Resend

Resend API Skill

Quick Start

Resend focuses on developer experience, bypassing legacy SMTP complexity. It inherently supports React Email for component-driven templating.

npm install resend react-email

Common Workflows

Transactional Emails

Trigger confirmation emails immediately after Stripe webhooks or Clerk user creations. Combine Resend with React Email to construct type-safe, cross-client compatible email components.

Production Patterns

Batch Sending

When notifying thousands of users (e.g., product updates), do not iterate resend.emails.send(). Instead, construct an array of payload objects and utilize resend.batch.send() to drastically reduce API latency and HTTP overhead.

Error Recovery

Handle ResendError. If sending fails due to HTTP 429 (Rate Limit), implement a dead-letter queue (DLQ) in your architecture (via SQS or Redis) to automatically retry the payload. Watch for bounce events via Webhooks.

Security Notes

Enforce Domain Authentication (DKIM/SPF/DMARC) in the Resend dashboard immediately. Unverified domains will land in spam or be outright rejected by Gmail and Outlook. Rotate API keys if exposed, as they possess sending authority.

Performance Considerations

HTML payloads can become large. Do not attach files larger than 10MB directly; instead, upload large attachments to an S3 bucket and provide a presigned URL within the email body.

Testing Guidance

Use the resend.emails.send endpoint with a verified testing domain or route traffic to a local mailcatcher during CI/CD. Do not blast real emails to mock users.

Troubleshooting

If emails mysteriously drop, check the Resend Dashboard 'Logs' tab. Statuses like 'Bounced' usually indicate a hard rejection by the receiving mail server. Ensure your from domain matches the authenticated domain.

References

• API Reference

Related Skills

• React-Email
• Stripe
• Clerk

Why use this skill

Use this when your agent works with resend — structured patterns beat pasted docs and prevent common hallucinations.

AI pitfalls

• Using outdated SDK or API versions from training data
• Inventing environment variable names
• Omitting error handling and retry logic

Production checklist

• Secrets in environment variables, not source code
• Error handling and logging in place
• Rate limits and timeouts configured

Related skills

• react-email — related to
• stripe — related to
• clerk — related to

Last Verified: 2026-07-02