Resend Expert

Complete Resend email API expertise for transactional emails, marketing broadcasts, and contact management.

Quick Reference

Auth: Authorization: Bearer $RESEND_API_KEY

User's Key: re_Czsz1gQW_Dz4H2a9dH8tTjgteeDCjVujF

Verified Domain: sigstack.dev (newsletter: tips@sigstack.dev)

Core Endpoints

Send Single Email

curl -X POST https://api.resend.com/emails
-H "Authorization: Bearer re_Czsz1gQW_Dz4H2a9dH8tTjgteeDCjVujF"
-H "Content-Type: application/json"
-d '{ "from": "SigStack Tips <tips@sigstack.dev>", "to": ["recipient@example.com"], "subject": "Hello", "html": "<p>Email body</p>" }'

Response: {"id": "uuid-string"}

Send Batch Emails (up to 100)

POST https://api.resend.com/emails/batch

Body: Array of email objects (same structure as single)

Note: No attachments or scheduling in batch mode

Get/Update/Cancel Email

GET /emails/{id} # Retrieve email details PATCH /emails/{id} # Update scheduled email DELETE /emails/{id}/cancel # Cancel scheduled email

Node.js SDK

npm install resend

import { Resend } from 'resend'; const resend = new Resend('re_Czsz1gQW_Dz4H2a9dH8tTjgteeDCjVujF');

// Send email const { data, error } = await resend.emails.send({ from: 'SigStack <hello@sigstack.dev>', to: ['user@example.com'], subject: 'Welcome!', html: '<h1>Hello World</h1>', });

// With React Email component const { data, error } = await resend.emails.send({ from: 'SigStack Tips <tips@sigstack.dev>', to: ['user@example.com'], subject: 'Welcome!', react: <WelcomeEmail name="User" />, });

// Batch send const { data, error } = await resend.batch.send([ { from: '...', to: ['...'], subject: '...', html: '...' }, { from: '...', to: ['...'], subject: '...', html: '...' }, ]);

Python SDK

pip install resend

import resend resend.api_key = "re_Czsz1gQW_Dz4H2a9dH8tTjgteeDCjVujF"

Send email

email = resend.Emails.send({ "from": "SigStack <hello@sigstack.dev>", "to": ["user@example.com"], "subject": "Hello", "html": "<p>Welcome!</p>" })

With attachments

email = resend.Emails.send({ "from": "...", "to": ["..."], "subject": "...", "html": "...", "attachments": [ {"filename": "invoice.pdf", "content": base64_content} ] })

Email Parameters

Parameter Type Required Description

from

string Yes "Name <email@domain>" format

string[] Yes Recipients (max 50)

subject

string Yes Subject line

html

string No* HTML body

text

string No* Plain text (auto-generated from html if omitted)

react

ReactNode No* React Email component (Node.js only)

string[] No Carbon copy

bcc

string[] No Blind carbon copy

reply_to

string[] No Reply-to addresses

scheduled_at

string No ISO 8601 or natural language

attachments

array No {filename, content, content_type?}

Prevents duplicate sends within 24 hours

Contact Management

Create contact

POST /contacts {"email": "user@example.com", "first_name": "John", "unsubscribed": false}

List contacts

GET /contacts?limit=50

Update contact

PATCH /contacts/{id}

Delete contact

DELETE /contacts/{id}

Domain Management

List domains

GET /domains?limit=20

Create domain

POST /domains {"name": "yourdomain.com"}

Verify domain

POST /domains/{id}/verify

Delete domain

DELETE /domains/{id}

Webhooks

Events: email.sent , email.delivered , email.bounced , email.complained , email.opened , email.clicked , contact.created , contact.updated , contact.deleted

Create webhook

POST /webhooks {"url": "https://yourapp.com/webhook", "events": ["email.delivered", "email.bounced"]}

Signature Verification (Node.js):

import { Webhook } from 'resend'; const webhook = new Webhook(process.env.RESEND_WEBHOOK_SECRET); const payload = webhook.verify(body, headers);

Templates

Create template

POST /templates {"name": "welcome", "html": "<p>Hello {{name}}</p>"}

Send with template

POST /emails {"from": "...", "to": ["..."], "template": {"id": "template-id", "variables": {"name": "John"}}}

API Keys

Create key

POST /api-keys {"name": "production", "permission": "sending_access"}

permission: "full_access" | "sending_access"

List keys

GET /api-keys

Delete key

DELETE /api-keys/{id}

Rate Limits & Quotas

Free tier: 100 emails/day, 3,000/month
Batch: Max 100 emails per request
Recipients: Max 50 per email
Attachments: Max 40MB total

Testing Domain

Use onboarding@resend.dev as sender for testing before domain verification.

SDKs

Node.js, Python, PHP, Laravel, Ruby, Go, Rust, Java, .NET

Common Patterns

Newsletter (tips@sigstack.dev):

await resend.emails.send({ from: 'SigStack Tips <tips@sigstack.dev>', to: [subscriber.email], subject: 'Weekly Dev Tips', html: newsletterHtml, });

Transactional (noreply@sigstack.dev):

await resend.emails.send({ from: 'SigStack <noreply@sigstack.dev>', to: [user.email], subject: 'Reset your password', react: <PasswordResetEmail token={token} />, });

Marketing broadcast:

// Use Broadcasts API for marketing campaigns with unsubscribe handling POST /broadcasts

Verified Sender Addresses

tips@sigstack.dev
newsletter
hello@sigstack.dev
general contact
noreply@sigstack.dev
transactional
*@sigstack.dev
any address works

Use when: Sending transactional emails, marketing campaigns, contact management, domain setup, webhook configuration

resend expert

Safety Notice

Copy this and send it to your AI assistant to learn