npm install nodemailer
//这个模块不错，github上星也比较多，还经常有维护，但是坑也比较多

npm install emailjs --save

npm install nodemailer --save

var nodemailer = require('nodemailer');
var transporter = nodemailer.createTransport({
  //https://github.com/andris9/nodemailer-wellknown#supported-services 支持列表
  service: 'qq',
  port: 465, // SMTP 端口
  secureConnection: true, // 使用 SSL
  auth: {
    user: '768065158@qq.com',
    //这里密码不是qq密码，是你设置的smtp密码
    pass: '*****'
  }
});
// NB! No need to recreate the transporter object. You can use
// the same transporter object for all e-mails
// setup e-mail data with unicode symbols
var mailOptions = {
  from: '768065158@qq.com', // 发件地址
  to: '528779822@qq.com', // 收件列表
  subject: 'Hello sir', // 标题
  //text和html两者只支持一种
  text: 'Hello world ?', // 标题
  html: '<b>Hello world ?</b>' // html 内容
};
// send mail with defined transport object
transporter.sendMail(mailOptions, function(error, info){
  if(error){
    return console.log(error);
  }
  console.log('Message sent: ' + info.response);
});

npm install nodemailer-smtp-transport --save

var nodemailer = require('nodemailer');
var smtpTransport = require('nodemailer-smtp-transport');
// 开启一个 SMTP 连接池
var transport = nodemailer.createTransport(smtpTransport({
 host: "smtp.qq.com", // 主机
 secure: true, // 使用 SSL
 secureConnection: true, // 使用 SSL
 port: 465, // SMTP 端口
 auth: {
  user: "gaolu19901228@qq.com", // 账号
  pass: "******" // 密码
 }
}));
// 设置邮件内容
var mailOptions = {
 from: "768065158<768065158@qq.com>", // 发件地址
 to: "528779822@qq.com", // 收件列表
 subject: "Hello world", // 标题
 text:"hello",
 html: "<b>thanks a for visiting!</b> 世界，你好！" // html 内容
}
// 发送邮件
transport.sendMail(mailOptions, function(error, response) {
 if (error) {
  console.error(error);
 } else {
  console.log(response);
 }
 transport.close(); // 如果没用，关闭连接池
});

{ [AuthError: Invalid login - 454 Authentication failed, please open smtp flag first!]
 name: 'AuthError',
 data: '454 Authentication failed, please open smtp flag first!',
 stage: 'auth' }

{ [SenderError: Mail from command failed - 501 mail from address must be same as authorization user]
name: 'SenderError',
data: '501 mail from address must be same as authorization user',
stage: 'mail' }

Invalid login - 535 Authentication failed