Resend

Overview

The Resend block lets you send emails through the Resend API directly from your workflows. It supports HTML and plain text content, CC/BCC, reply-to, scheduled delivery, tagging, attachments, batch sending, and email retrieval/cancellation.

When to Use

• Send transactional emails (welcome, password reset, receipts)
• Send marketing or notification emails from workflows
• Batch send personalized emails to multiple recipients
• Schedule emails for future delivery
• Retrieve email status or cancel scheduled emails

Prerequisites

1. Create a Resend account at resend.com
2. Add and verify your sending domain at resend.com/domains
3. Generate an API key at resend.com/api-keys

Add Your Domain (Step by Step)

Use this flow for production email sending.

1. Open Resend Domains and click Add Domain.
2. Enter your domain (example: yourdomain.com) and submit.
3. Copy the DNS records Resend gives you (commonly SPF, DKIM, and optionally DMARC).
4. Open your DNS provider (Cloudflare, GoDaddy, Namecheap, Route53, etc.) and add those exact records.
5. Wait for DNS propagation, then click Verify DNS Records in Resend.
6. After verification succeeds, use a sender address from that domain, for example:
   • hello@yourdomain.com
   • Acme <notifications@yourdomain.com>

Notes About Domain Verification

• If verification is pending, wait a few minutes and re-check DNS record values and host names.
• For production, always send from your verified domain.
• onboarding@resend.dev is only for testing and evaluation.

Generate API Key (Step by Step)

1. Open Resend API Keys.
2. Click Create API Key.
3. Choose the key permission scope you need.
4. Name the key clearly (example: zelaxy-production).
5. Copy the key immediately and store it securely (Resend shows it once).

API keys start with re_.

Next.js Integration Reference

Official guide: Send email with Next.js

Minimal Next.js example using an API route:

import { Resend } from 'resend'

const resend = new Resend(process.env.RESEND_API_KEY)

export async function POST() {
  const { data, error } = await resend.emails.send({
    from: 'Acme <notifications@yourdomain.com>',
    to: ['user@example.com'],
    subject: 'Hello from Next.js',
    html: '<p>It works.</p>',
  })

  return Response.json({ data, error })
}

Add your environment variable:

RESEND_API_KEY=re_xxxxxxxxxxxxxxxxx

Restart your app after changing .env files.

Use Resend in Zelaxy

1. Add a Resend block in your workflow.
2. Set API Key with your re_... key.
3. Set From to an address on your verified domain.
4. Choose action (Send, Batch Send, Get Email, Cancel Scheduled).
5. Fill required fields and run the workflow.

Configuration

Send Email Fields

* At least one of HTML Body or Plain Text Body is required.

Advanced Send Fields

Batch Send Fields

Get / Cancel Fields

Outputs

Examples

Basic Email

Send a simple HTML email:

[Starter] → [Resend] → [Response]

Configure the Resend block:

• API Key: Your re_ key
• From: Acme <notifications@yourdomain.com>
• To: {{starter.email}}
• Subject: Welcome to Acme!
• HTML Body: <h1>Welcome!</h1><p>Thanks for signing up.</p>

Development Testing

For quick testing before domain setup:

• From: onboarding@resend.dev
• To: your own inbox

Then switch to your verified domain sender for production.

Scheduled Email

Send a reminder email in the future:

• Schedule At: 2026-12-25T09:00:00Z or in 1 hour

Batch Send

Send personalized emails to multiple recipients at once:

[
  {
    "from": "Acme <hello@yourdomain.com>",
    "to": "alice@example.com",
    "subject": "Hi Alice",
    "html": "<p>Hello Alice!</p>"
  },
  {
    "from": "Acme <hello@yourdomain.com>",
    "to": "bob@example.com",
    "subject": "Hi Bob",
    "html": "<p>Hello Bob!</p>"
  }
]

Tags for Tracking

Add tags to categorize and track emails:

[
  { "name": "category", "value": "welcome" },
  { "name": "user_id", "value": "12345" }
]

Retrieve Email Status

Use the Get Email action with an email ID from a previous send to check its delivery status.

Cancel a Scheduled Email

Use the Cancel Scheduled Email action with the email ID to cancel a previously scheduled email before it's delivered.

Tips

• Use a verified domain in the from address for production. The test address onboarding@resend.dev only works for testing.
• Resend provides test addresses for simulating events: delivered@resend.dev, bounced@resend.dev, complained@resend.dev, suppressed@resend.dev.
• The default rate limit is 5 requests/second per team.
• Scheduled emails can be sent up to 30 days in advance.
• Tags are useful for filtering and analytics in the Resend dashboard.
• Attachment total size limit is 40 MB per email (after encoding).
• For idempotent sends (retry-safe), use a unique idempotency key pattern like welcome-user/123456789.