Resend Box Skill

Resend Box is a local email sandbox that:

1. Mocks the Resend API - Drop-in replacement for https://api.resend.com
2. Runs an SMTP server - Captures emails sent via SMTP on port 1025
3. Provides a Web UI - View captured emails at http://127.0.0.1:4657
4. Stores emails in-memory - All emails are lost when the server restarts

When to Use

• You're using the Resend SDK and want to test emails locally
• You're sending emails via SMTP and need to verify they're sent correctly
• You want to inspect email content (HTML, text, headers) during development
• You need to verify emails are sent to the correct recipients
• You're testing email templates before sending to real users

Prerequisites

Start Resend Box:

npx resend-box start

Configure your project to use the sandbox - see Setup Guide.

Quick Reference

Send an Email (via Resend API)

curl -X POST http://127.0.0.1:4657/emails \
  -H "Content-Type: application/json" \
  -d '{
    "from": "sender@example.com",
    "to": "recipient@example.com",
    "subject": "Test Email",
    "html": "<p>Hello!</p>"
  }'

Required fields: from, to, subject
Optional fields: html, text, cc, bcc, replyTo

Get All Emails

curl http://127.0.0.1:4657/sandbox/emails

Filter Emails by Recipient

curl "http://127.0.0.1:4657/sandbox/emails?to=user@example.com"

The to filter is case-insensitive and supports partial matching.

Get a Specific Email

curl http://127.0.0.1:4657/sandbox/emails/{id}

Delete All Emails

curl -X DELETE http://127.0.0.1:4657/sandbox/emails

View in Browser

Open http://127.0.0.1:4657 to view captured emails in the web UI.

Detailed Documentation

• Setup Guide - Configure your project to use Resend Box
• Send Email Reference - Complete API for sending emails
• Get Emails Reference - Complete API for retrieving and filtering emails