Send Email with Express

This guide shows you how to send transactional emails using Sequenzy in an Express application.

Prerequisites

A Sequenzy account with an API key
A verified sending domain
Node.js 18+ installed

1. Install

Install the Sequenzy SDK and Express:

npm install sequenzy express

pnpm add sequenzy express

bun add sequenzy express

For TypeScript support:

npm install -D @types/express typescript

2. Create Your Server

Create a basic Express server that sends emails:

index.ts

import express, { Request, Response } from "express";
import Sequenzy from "sequenzy";

const app = express();
app.use(express.json());

const client = new Sequenzy({
  apiKey: process.env.SEQUENZY_API_KEY!,
});

app.post("/send", async (req: Request, res: Response) => {
  const { email, firstName } = req.body;

  const { data, error } = await client.transactional.send({
    to: email,
    subject: "Welcome to Our Platform!",
    body: `<h1>Welcome, ${firstName}!</h1><p>Thanks for signing up.</p>`,
  });

  if (error) {
    return res.status(400).json({ error });
  }

  return res.status(200).json({ data });
});

app.listen(3000, () => {
  console.log("Server running at http://localhost:3000");
});

3. Run

Start your server:

npx tsx index.ts

Send a test request:

curl -X POST http://localhost:3000/send \
  -H "Content-Type: application/json" \
  -d '{"email": "user@example.com", "firstName": "John"}'

Using Templates

Instead of inline HTML, use pre-built templates from the Sequenzy dashboard:

app.post("/send-welcome", async (req: Request, res: Response) => {
  const { email, firstName } = req.body;

  const { data, error } = await client.transactional.send({
    to: email,
    slug: "welcome-email",
    variables: {
      firstName,
      dashboardUrl: "https://app.example.com/dashboard",
    },
  });

  if (error) {
    return res.status(400).json({ error });
  }

  return res.status(200).json({ data });
});

Using React Email

For complex email templates, use React Email with Express:

npm install @react-email/components @react-email/render

Create a template:

emails/welcome-email.tsx

import {
  Body,
  Button,
  Container,
  Head,
  Heading,
  Html,
  Preview,
  Text,
} from "@react-email/components";
import * as React from "react";

interface WelcomeEmailProps {
  firstName: string;
  dashboardUrl: string;
}

export function WelcomeEmail({ firstName, dashboardUrl }: WelcomeEmailProps) {
  return (
    <Html>
      <Head />
      <Preview>Welcome to our platform</Preview>
      <Body style={{ fontFamily: "sans-serif", padding: "20px" }}>
        <Container>
          <Heading>Welcome, {firstName}!</Heading>
          <Text>
            Thanks for signing up. Get started by visiting your dashboard:
          </Text>
          <Button
            href={dashboardUrl}
            style={{
              backgroundColor: "#c95a3c",
              color: "white",
              padding: "12px 24px",
              borderRadius: "6px",
            }}
          >
            Go to Dashboard
          </Button>
        </Container>
      </Body>
    </Html>
  );
}

Use it in your route:

import { render } from "@react-email/render";
import { WelcomeEmail } from "./emails/welcome-email";

app.post("/send-welcome", async (req: Request, res: Response) => {
  const { email, firstName } = req.body;

  const html = await render(
    WelcomeEmail({
      firstName,
      dashboardUrl: "https://app.example.com/dashboard",
    })
  );

  const { data, error } = await client.transactional.send({
    to: email,
    subject: "Welcome to Our Platform!",
    body: html,
  });

  if (error) {
    return res.status(400).json({ error });
  }

  return res.status(200).json({ data });
});

Error Handling

Add proper error handling for production:

app.post("/send", async (req: Request, res: Response) => {
  try {
    const { email, firstName } = req.body;

    if (!email || !firstName) {
      return res
        .status(400)
        .json({ error: "Email and firstName are required" });
    }

    const { data, error } = await client.transactional.send({
      to: email,
      slug: "welcome-email",
      variables: { firstName },
    });

    if (error) {
      console.error("Email sending failed:", error);
      return res.status(400).json({ error });
    }

    return res.status(200).json({ data });
  } catch (err) {
    console.error("Unexpected error:", err);
    return res.status(500).json({ error: "Internal server error" });
  }
});

Get Started

Send Email

Core Concepts

Email Features

SMS

Analytics

Deliverability

Guides

Widgets

Payment Integrations

Commerce Integrations

Website Integrations

Auth Integrations

Analytics Integrations

Ad Integrations

Affiliate Integrations

Automation Integrations

Developer Tools

Send Email with Express

Send Email with Express

Prerequisites

1. Install

2. Create Your Server

3. Run

Using Templates

Using React Email

Error Handling

Next Steps

React Email Components

Transactional Emails

​Send Email with Express

​Prerequisites

​1. Install

​2. Create Your Server

​3. Run

​Using Templates

​Using React Email

​Error Handling

​Next Steps

React Email Components

Transactional Emails

Send Email with Express

Prerequisites

1. Install

2. Create Your Server

3. Run

Using Templates

Using React Email

Error Handling

Next Steps