Transactional email has a bad reputation for being fiddly to set up right — Resend's whole pitch is that sending an email from your app should be as simple as any other API call, without sacrificing deliverability.
Resend is a transactional email API built for developers, with first-class support for React Email (writing email templates as React components), straightforward domain verification, and webhook-based delivery event tracking. It's a notably good fit for teams already working in a React/Next.js stack, since templates can be written and previewed the same way as any other component.
Why Resend Matters (and When to Skip It)
Email deliverability is a genuinely hard problem — SPF, DKIM, DMARC, IP reputation, and spam filtering all affect whether an email actually reaches an inbox. Resend handles the infrastructure side of this while giving you a clean API and React-based templating on top, which is a meaningfully better developer experience than most legacy transactional email providers.
Skip Resend if you're already deeply invested in another provider (SendGrid, Postmark) without a compelling reason to migrate — deliverability reputation is somewhat tied to sending history, so switching providers isn't entirely free.
Getting Started with Resend
import { Resend } from "resend";
const resend = new Resend(process.env.RESEND_API_KEY);
await resend.emails.send({
from: "onboarding@yourdomain.com",
to: "user@example.com",
subject: "Welcome to the app",
html: "<p>Thanks for signing up!</p>",
});
Using a React Email template:
// emails/welcome.tsx
import { Html, Body, Heading, Text } from "@react-email/components";
export function WelcomeEmail({ name }: { name: string }) {
return (
<Html>
<Body>
<Heading>Welcome, {name}!</Heading>
<Text>Thanks for signing up. Let's get started.</Text>
</Body>
</Html>
);
}
import { WelcomeEmail } from "./emails/welcome";
await resend.emails.send({
from: "onboarding@yourdomain.com",
to: user.email,
subject: "Welcome!",
react: WelcomeEmail({ name: user.name }),
});
Core Resend Concepts Every Developer Should Know
Domain verification (SPF/DKIM) is required for good deliverability, not optional. Sending from an unverified domain, or Resend's shared default domain, significantly hurts inbox placement — verifying your own sending domain with the DNS records Resend provides is a necessary first step for any real production use.
React Email templates are just React components, rendered to HTML at send time — this means you get component reuse, TypeScript props, and a live preview server for templates, a meaningfully better authoring experience than raw HTML string templates.
Webhooks provide delivery event tracking (delivered, bounced, complained, opened) that lets your application react to email outcomes — for example, marking an address as invalid after a hard bounce, rather than continuing to send to it.
app.post("/webhooks/resend", (req, res) => {
const event = req.body;
if (event.type === "email.bounced") {
markEmailInvalid(event.data.to);
}
res.sendStatus(200);
});
Batch sending is a distinct API for sending many emails efficiently, worth using instead of looping individual send calls when dispatching to a large recipient list.
Common Resend Mistakes and How to Fix Them
Mistake 1: sending from an unverified domain in production. This tanks deliverability and often lands in spam. Fix: verify your sending domain with the provided DNS records before sending real production email.
Mistake 2: no bounce/complaint handling, continuing to send to addresses that have hard-bounced or marked email as spam. This actively damages sender reputation over time. Fix: consume delivery webhooks and suppress future sends to bad addresses.
Mistake 3: putting complex conditional logic directly in HTML templates instead of using React Email components. This makes templates hard to maintain and test. Fix: build templates as proper React components with typed props, using the standard React patterns you'd use anywhere else.
When Should You Use Resend Instead of SendGrid or Postmark?
Use Resend when you want a modern developer experience, React Email templating, and are building in a React/Next.js-centric stack. Use SendGrid or another established provider when you need specific enterprise features, existing sender reputation you don't want to disrupt, or marketing email capabilities (as opposed to purely transactional) that Resend doesn't focus on.
Resend Email API in Production
Set up webhook handling for bounce and complaint events from day one — reputation damage from ignoring these compounds over time and is hard to reverse. Also monitor delivery rates and investigate any unexpected drop, since deliverability issues are often silent until someone notices missing emails.
Before sending real user email, verify your domain and confirm delivery events are being consumed — those two things determine whether emails actually reach inboxes reliably.