npm install nodemailernpm install -D @types/nodemailer

// src/config/mail.tsimport nodemailer from 'nodemailer'; const transporter = nodemailer.createTransport({  host: process.env.MAIL_HOST,  port: Number(process.env.MAIL_PORT),  secure: process.env.MAIL_SECURE === 'true',  auth: {    user: process.env.MAIL_USER,    pass: process.env.MAIL_PASS,  },}); export default transporter;

// src/services/mail.service.tsimport transporter from '../config/mail'; interface SendMailOptions {  to: string;  subject: string;  html: string;} export class MailService {  private from = `"E-commerce" <${process.env.MAIL_FROM}>`;   async send({ to, subject, html }: SendMailOptions): Promise<void> {    await transporter.sendMail({ from: this.from, to, subject, html });  }   async sendWelcome(user: { name: string; email: string }): Promise<void> {    await this.send({      to: user.email,      subject: 'Welcome to E-commerce!',      html: `        <h1>Hello, ${user.name}!</h1>        <p>Your account was created successfully.</p>      `,    });  }   async sendPasswordReset(user: { email: string }, token: string): Promise<void> {    const resetUrl = `${process.env.FRONTEND_URL}/reset-password?token=${token}`;     await this.send({      to: user.email,      subject: 'Password Reset',      html: `        <h1>Password Reset</h1>        <p>Click the link below to reset your password:</p>        <a href="${resetUrl}">Reset Password</a>        <p>Link expires in 1 hour.</p>      `,    });  }   async sendOrderConfirmation(user: { name: string; email: string }, order: any): Promise<void> {    await this.send({      to: user.email,      subject: `Order #${order.id} Confirmed`,      html: `        <h1>Order Confirmed!</h1>        <p>Thank you for your purchase, ${user.name}!</p>        <p><strong>Total: $${order.total}</strong></p>      `,    });  }}

npm install bullnpm install -D @types/bull

// src/jobs/mail.job.tsimport Bull from 'bull';import { MailService } from '../services/mail.service'; const mailQueue = new Bull('mail', { redis: process.env.REDIS_URL });const mailService = new MailService(); mailQueue.process(async (job) => {  await mailService.send(job.data);}); export const addMailJob = (data: SendMailOptions) => {  return mailQueue.add(data, {    attempts: 3,    backoff: { type: 'exponential', delay: 2000 },  });};