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Documentation Index

Fetch the complete documentation index at: https://docs.lettr.com/llms.txt

Use this file to discover all available pages before exploring further.

Learn how to integrate Lettr with your Next.js application.

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Installation

npm install lettr

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Environment Setup

Add your API key to .env.local: 
LETTR_API_KEY=your-api-key

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API Route (App Router)

Create app/api/email/route.ts: 
import { NextResponse } from 'next/server';
import { Lettr } from 'lettr';

const lettr = new Lettr(process.env.LETTR_API_KEY!);

export async function POST(request: Request) {
  const { to, subject, html } = await request.json();

  try {
    const data = await lettr.emails.send({
      from: 'you@example.com',
      to: [to],
      subject,
      html
    });

    return NextResponse.json(data);
  } catch (error) {
    return NextResponse.json({ error: error.message }, { status: 500 });
  }
}

​
Server Actions

Create app/actions/email.ts: 
'use server';

import { Lettr } from 'lettr';

const lettr = new Lettr(process.env.LETTR_API_KEY!);

export async function sendContactEmail(formData: FormData) {
  const email = formData.get('email') as string;
  const name = formData.get('name') as string;
  const message = formData.get('message') as string;

  await lettr.emails.send({
    from: 'contact@example.com',
    to: ['team@example.com'],
    subject: `Contact from ${name}`,
    html: `
      <h2>New Contact Message</h2>
      <p><strong>From:</strong> ${name} (${email})</p>
      <p><strong>Message:</strong></p>
      <p>${message}</p>
    `
  });

  return { success: true };
}

​
Contact Form Component

'use client';

import { sendContactEmail } from '@/app/actions/email';
import { useFormStatus } from 'react-dom';

function SubmitButton() {
  const { pending } = useFormStatus();
  return (
    <button type="submit" disabled={pending}>
      {pending ? 'Sending...' : 'Send Message'}
    </button>
  );
}

export function ContactForm() {
  return (
    <form action={sendContactEmail}>
      <input name="name" placeholder="Your name" required />
      <input name="email" type="email" placeholder="Your email" required />
      <textarea name="message" placeholder="Your message" required />
      <SubmitButton />
    </form>
  );
}

​
React Email Integration

Use React Email for beautiful templates: 
npm install @react-email/components

// emails/welcome.tsx
import { Html, Head, Body, Container, Text, Button } from '@react-email/components';

export function WelcomeEmail({ name }: { name: string }) {
  return (
    <Html>
      <Head />
      <Body>
        <Container>
          <Text>Welcome, {name}!</Text>
          <Button href="https://example.com/dashboard">
            Get Started
          </Button>
        </Container>
      </Body>
    </Html>
  );
}

// app/api/welcome/route.ts
import { Lettr } from 'lettr';
import { render } from '@react-email/render';
import { WelcomeEmail } from '@/emails/welcome';

const lettr = new Lettr(process.env.LETTR_API_KEY!);

export async function POST(request: Request) {
  const { email, name } = await request.json();
  
  const html = render(<WelcomeEmail name={name} />);

  await lettr.emails.send({
    from: 'welcome@example.com',
    to: [email],
    subject: 'Welcome to Our App!',
    html
  });

  return Response.json({ success: true });
}