Nodemailer SMTP Provider

This provider configures Nodemailer with SMTP settings from the environment, validates host/port/credentials with Zod, and exposes a lazy singleton getTransporter() for sending mail.

Features

Zod schema for SMTP_* and EMAIL_FROM
Single reused transporter instance
TLS mode inferred from port (secure when port is 465)
MVC and Feature architecture variants

Installation Guide

npx servercn-cli add pr nodemailer-smtp

File Structure

MVC

src/configs/env.ts
src/configs/nodemailer.ts

Feature

src/shared/configs/env.ts
src/shared/configs/nodemailer.ts

Environment Configuration

src/configs/env.ts

import "dotenv-flow/config";
import { z } from "zod";
 
export const envSchema = z.object({
  SMTP_HOST: z.string(),
  SMTP_PORT: z
    .string()
    .regex(/^\d+$/, "SMTP_PORT must be a number")
    .transform(Number),
  SMTP_USER: z.string(),
  SMTP_PASS: z.string(),
  EMAIL_FROM: z.email()
});
 
export type Env = z.infer<typeof envSchema>;
 
const result = envSchema.safeParse(process.env);
 
if (!result.success) {
  console.error("❌ Invalid environment configuration");
  console.error(z.prettifyError(result.error));
  process.exit(1);
}
 
export const env: Readonly<Env> = Object.freeze(result.data);
 
export default env;

Nodemailer transporter

src/configs/nodemailer.ts

import nodemailer from "nodemailer";
import env from "./env";
 
let transporter: nodemailer.Transporter | null = null;
 
export function getTransporter() {
  if (transporter) return transporter;
  const host = env.SMTP_HOST;
  const port = Number(env.SMTP_PORT || 465);
  const user = env.SMTP_USER;
  const pass = env.SMTP_PASS;
  const from = env.EMAIL_FROM;
  if (!host || !user || !pass || !from) {
    throw new Error("SMTP/EMAIL env not configured");
  }
 
  transporter = nodemailer.createTransport({
    host,
    port,
    secure: port === 465,
    auth: { user, pass }
  });
  return transporter;
}

Usage

import env from "./configs/env";
import { getTransporter } from "./configs/nodemailer";
 
export async function sendEmail(opts: {
  to: string;
  subject: string;
  html: string;
  from?: string;
}) {
  const transporter = getTransporter();
  return transporter.sendMail({
    from: opts.from ?? env.EMAIL_FROM,
    to: opts.to,
    subject: opts.subject,
    html: opts.html
  });
}

Example .env

SMTP_HOST=smtp.example.com
SMTP_PORT=465
SMTP_USER=you@example.com
SMTP_PASS=your_password
EMAIL_FROM=you@example.com