NodeMailer 登录无效

I am new to node.js programming .I am using nodemailer module for sending emails.

const nodemailer = require ('nodemailer'),
credentials=require('./credentials.js');
var mailTransport=nodemailer.createTransport({
    service:'Gmail',
    auth: {
        user : credentials.gmail.user,
        pass : credentials.gmail.password,
    }
});
function sendMail(mail_id){
    mailTransport.sendMail({
        from: ' "my name" <myname@gmail.com>',
        to : mail_id,   //user@gmail.com
        subject : 'Hello',
        text: "Hello How do u do ?",
    },function(err,info){
        if(err){
            console.log('Unable to send the mail :'+err.message);
        }
        else{
            console.log('Message response : '+info.response);
        }
    });
}
exports.sendMail=sendMail;

这是我向不同用户发送电子邮件的程序.但我得到 Invalid Login .我不知道为什么会这样.我是 node.js 和服务器端脚本的新手.
我正在使用我的 gmail 用户名和密码作为凭据.
请帮帮我.