Send email with Next.js

// lib/poststack.ts
import 'server-only';
import { PostStack } from '@poststack.dev/sdk';

export const poststack = new PostStack(process.env.POSTSTACK_API_KEY!);

// app/contact/actions.ts
'use server';
import { poststack } from '@/lib/poststack';

export async function sendContact(formData: FormData) {
  const email = String(formData.get('email'));
  const message = String(formData.get('message'));

  await poststack.emails.send({
    from: 'Acme Support <support@yourdomain.com>',   // a verified domain
    to: ['support@yourdomain.com'],
    reply_to: email,                                  // replies go to the visitor
    subject: 'New contact form message',
    text: message,
  });
}

// app/contact/page.tsx
import { sendContact } from './actions';

export default function ContactPage() {
  return (
    <form action={sendContact}>
      <input name="email" type="email" required />
      <textarea name="message" required />
      <button type="submit">Send</button>
    </form>
  );
}

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

export function WelcomeEmail({ name }: { name: string }) {
  return (
    <Html>
      <Body>
        <Text>Welcome, {name}!</Text>
        <Button href="https://yourdomain.com/start">Get started</Button>
      </Body>
    </Html>
  );
}

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

export async function POST(req: Request) {
  const { email, name } = (await req.json()) as { email: string; name: string };
  const html = await render(<WelcomeEmail name={name} />);
  const text = await render(<WelcomeEmail name={name} />, { plainText: true });

  const { id } = await poststack.emails.send({
    from: 'Acme <hello@yourdomain.com>',
    to: [email],
    subject: 'Welcome to Acme',
    html,
    text,
  });
  return Response.json({ id });
}

const { id } = await poststack.emails.send({
  from: 'Acme <hello@yourdomain.com>',
  to: [user.email],
  template_id: 'tpl_…',                     // from the Templates page
  variables: { first_name: user.firstName, plan: 'Pro' },
});

// app/api/invoice/route.ts
import { readFile } from 'node:fs/promises';
import path from 'node:path';
import { poststack } from '@/lib/poststack';

export async function POST(req: Request) {
  const { to, invoiceId } = (await req.json()) as { to: string; invoiceId: string };
  const pdf = await renderInvoicePdf(invoiceId);                 // Buffer / Uint8Array
  const logo = await readFile(path.join(process.cwd(), 'public/logo.png'));

  const { id } = await poststack.emails.send({
    from: 'Acme Billing <billing@yourdomain.com>',
    to: [to],
    subject: `Invoice ${invoiceId}`,
    html: '<img src="cid:logo" alt="Acme" width="120"><p>Your invoice is attached.</p>',
    attachments: [
      { filename: `invoice-${invoiceId}.pdf`, content: Buffer.from(pdf).toString('base64') },
      { filename: 'logo.png', content: logo.toString('base64'), content_id: 'logo' },
    ],
  });
  return Response.json({ id });
}

// app/api/webhooks/poststack/route.ts
import { PostStack } from '@poststack.dev/sdk';

export async function POST(req: Request) {
  const raw = await req.text();                                    // exact bytes
  const ok = await PostStack.Webhooks.verify(
    raw,
    req.headers.get('X-PostStack-Signature') ?? '',
    process.env.POSTSTACK_WEBHOOK_SECRET!,                          // whsec_…
  );
  if (!ok) return new Response('Invalid signature', { status: 401 });

  const event = JSON.parse(raw) as {
    type: string;
    data: { email_id: string; to: string[]; bounce_message?: string };
  };
  switch (event.type) {
    case 'email.bounced':
      await db.user.updateMany({                                   // your ORM here
        where: { lastEmailId: event.data.email_id },
        data: { emailUndeliverable: true },
      });
      break;
    case 'email.complained':
      await unsubscribeEverywhere(event.data.to);
      break;
  }
  return new Response(null, { status: 204 });
}

// lib/mailer.ts
import 'server-only';
import nodemailer from 'nodemailer';

export const mailer = nodemailer.createTransport({
  host: 'smtp.poststack.dev',
  port: 465,
  secure: true,                                      // implicit TLS; or 587 + requireTLS
  auth: { user: 'poststack', pass: process.env.POSTSTACK_API_KEY! },
});

await mailer.sendMail({
  from: 'Acme <hello@yourdomain.com>',
  to: 'user@example.com',
  subject: 'Hello over SMTP',
  html: '<h1>Welcome!</h1>',
  headers: { 'X-PostStack-Tags': 'welcome' },
});