qq邮箱，先去qq邮箱设置中获取到授权码

var nodemailer = require("nodemailer");
var transporter = nodemailer.createTransport({
  service: "qq",
  auth: {
    user: "XXX@qq.com", //这里填自己的 qq号
    pass: "cqfib", //授权码,通过QQ邮箱获取
  },
});
var mailOptions = {
  from: "xx@qq.com", // 发送者 asdfghj
  to: ["xx", "xx@163.com"], // 接受者,可以同时发送多个,以逗号隔开
  subject: "nodemailer3.1.8邮件发送", // 标题
  text: "这是我发的一封邮件，如果你开心，我也开心^_^", // 文本
//   html: `<h2>nodemailer基本使用:</h2><h3> 
//  <a href="//www.greatytc.com/u/27f54f428a14" rel="external nofollow" > 
//  //www.greatytc.com/u/27f54f428a14</a></h3>`,
  attachments: [
    {
      filename: "package.json",
      path: "./package.json",
    },
    {
      filename: "content",
      content: "发送内容",
    },
    {
      filename: "index.html",
      path: "./index.html",
    },
  ],
};
transporter.sendMail(mailOptions, function (err, info) {
  if (err) {
    console.log(err);
    return;
  }
  console.log(info)
  console.log("发送成功");
  res.send("发送成功");
});

自己搭建的邮箱服务， 要数据用户名和密码， 指定服务ip和端口，开启ssl

var nodemailer = require("nodemailer");
const auth = process.env.auth
var transporter = nodemailer.createTransport({
  host: 'mapi.xxx.com',
  port: 587,
  secureConnection:true,
  auth
});
var mailOptions = {
  from: "xxx", // 发送者 asdfghj
  to: ["xxx", "xxx@163.com"], // 接受者,可以同时发送多个,以逗号隔开
  subject: "nodemailer3.1.8邮件发送", // 标题
  text: "这是我发的一封邮件，如果你开心，我也开心^_^", // 文本
//   html: `<h2>nodemailer基本使用:</h2><h3> 
//  <a href="//www.greatytc.com/u/27f54f428a14" rel="external nofollow" > 
//  //www.greatytc.com/u/27f54f428a14</a></h3>`,
  attachments: [
    {
      filename: "package.json",
      path: "./package.json",
    },
    {
      filename: "content",
      content: "发送内容",
    },
    {
      filename: "index.html",
      path: "./index.html",
    },
  ],
};
transporter.sendMail(mailOptions, function (err, info) {
  if (err) {
    console.log(err);
    return;
  }
  console.log(info)
  console.log("发送成功");
});