How to Send Transactional Emails from Hono

Hono is what we use for SendPigeon's API. We picked it because it's built on standard Web APIs instead of Node-specific stuff. Your application logic stays portable across Node.js, Cloudflare Workers, Bun, and Deno — only the server setup differs.

Here's how to send transactional emails from Hono.

---

Basic setup

npm install sendpigeon hono

import { Hono } from "hono";
import { SendPigeon } from "sendpigeon";

const app = new Hono();

app.post("/send", async (c) => {
  const client = new SendPigeon(process.env.SENDPIGEON_API_KEY!);
  const { to, subject, html } = await c.req.json();

  const { data, error } = await client.send({
    from: "hello@yourdomain.com",
    to,
    subject,
    html,
  });

  if (error) {
    return c.json({ error: error.message }, error.status);
  }

  return c.json({ id: data.id });
});

export default app;

---

Environment by runtime

Node.js

import { serve } from "@hono/node-server";

const client = new SendPigeon(process.env.SENDPIGEON_API_KEY!);

serve({ fetch: app.fetch, port: 3000 });

Cloudflare Workers

type Bindings = { SENDPIGEON_API_KEY: string };

const app = new Hono<{ Bindings: Bindings }>();

app.post("/send", async (c) => {
  const client = new SendPigeon(c.env.SENDPIGEON_API_KEY);
  // ...
});

Bun

const client = new SendPigeon(Bun.env.SENDPIGEON_API_KEY!);

Deno

const client = new SendPigeon(Deno.env.get("SENDPIGEON_API_KEY")!);

---

Validation with Zod

Use @hono/zod-openapi for validated, typed requests:

import { OpenAPIHono, createRoute, z } from "@hono/zod-openapi";

const sendEmailSchema = z.object({
  to: z.string().email(),
  subject: z.string().min(1).max(200),
  html: z.string(),
});

const sendRoute = createRoute({
  method: "post",
  path: "/send",
  request: {
    body: { content: { "application/json": { schema: sendEmailSchema } } },
  },
  responses: {
    200: {
      description: "Email sent",
      content: { "application/json": { schema: z.object({ id: z.string() }) } },
    },
  },
});

const app = new OpenAPIHono();

app.openapi(sendRoute, async (c) => {
  const body = c.req.valid("json"); // Fully typed
  // ...
});

---

Error handling

const { data, error } = await client.send({ from, to, subject, html });

if (error) {
  if (error.status === 429) {
    return c.json({ error: "Rate limited" }, 429);
  }
  return c.json({ error: error.message }, error.status || 500);
}

return c.json({ id: data.id });

---

Non-blocking emails

Cloudflare Workers:

app.post("/signup", async (c) => {
  const user = await createUser(data);
  c.executionCtx.waitUntil(sendWelcomeEmail(user.email));
  return c.json({ userId: user.id });
});

Node.js:

app.post("/signup", async (c) => {
  const user = await createUser(data);
  sendWelcomeEmail(user.email).catch(console.error);
  return c.json({ userId: user.id });
});

---

Testing

import { describe, it, expect } from "vitest";
import app from "./app";

describe("POST /send", () => {
  it("sends email", async () => {
    const res = await app.request("/send", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({
        to: "user@example.com",
        subject: "Test",
        html: "<p>Hello</p>",
      }),
    });

    expect(res.status).toBe(200);
  });
});

---

Next steps

• Framework Guides — More integrations
• Email Authentication — SPF, DKIM, DMARC
• API Docs — Full reference