示例代码：
const express = require('express');
const nodemailer = require('nodemailer');
const querystring = require('querystring');
const axios = require('axios');const app = express();
app.use(express.json());const transporter = nodemailer.createTransport({service: 'Outlook365', // 也可以用 'hotmail'auth: {type: 'OAuth2',user: 'sdkflja_ggg@outlook.com',clientId: '21f97687-903e-4806-903f-7c3162f73cea',clientSecret: 'Brp8Q~qBdngo.SLNfJbc83YgtPqnKnrgHuBq.c8f',refreshToken: 'M.C543_BL2.0.U.-CkdUriBwl1MEcv2WRP5ZLo2tVbmA0Lhgzn18IVcqhM8ZBrzEDTHng8FhWoByDcQpYyskZVKdRFjAzqAx5qjjx5NKpsahbm5P12VD9cPcX2f30ckbxTXeCmbcngguSbxx6SX7uumH2iPWZxS0HVsLXMhnxgnkNEW8dixb90jgc7uHQC!*lV1y8QjZbQNxzBucCSTDOIFuNIjM7k6UYC2lgjZPjvaQl66S1xXJp2YRoJ6w4KPwQ0zlOOUMLS7jpwLYEyUOHnzYPY5bCpk2bBhoE0xE6c0k*THxGsfN5xF2xJXyEVIJNUn!JRcsnpsQcPB1N1ggVpkf8fWVzeMgUECC7So!UKhLJbVZBNQldjUwoTH*yDMuGvo8SnIdmMELE1Wmlpb0JlSlTpgvTV*v*YTyesA$',accessToken: 'EwAIBOl3BAAUcDnR9grBJokeAHaUV8R3+rVHX+IAAf5LCOGj2z3+BP5D2doOw+E2jHHTT6tpaipG3TaJWxypwgJM68oAQ+t2441dbub+DUmJYTjRCAFSrxDSlVyapKUNRcknLCZEvfJ4dVCTK9IEksaY5MFq/3YlEU4FyJivTh8aLiUXKppmRQLPBPVhQF9ypsbwcWCLrcHLvaT0WJM2JW5Uq0nWA/KVwzcZSKymn8qNiiU1bt5KlkogbDNMzegjvTOPoKSCPok/R46IoJzBMoENRQlCt+W60HT94XF0hATWMl9kXUCqknuHORnZevGC1H4ECX9aTPS3qsmS182ZaigRx6rntfMrh1BaY2x5OlSbW/VUyfKlxvInCMBjMmEQZgAAEJKxntheAOYGkeSTC51dDVDQArKGCk757MKV9hFX8z0Sw8A6IQmh/Zxghe2PNL+q2JiX7wup/U1NvjoRaRESIlpToB8x+GZ+zzW4KNj7mUFM96Rb4ae1Vh19tqjLr0SP3kIv3g6+ybpoj7Xv2vEOav2xA7pPGshkGH7dYapBOYSee5tjV2ZZqIwt5HLz/nPuOpkkaoqx5jRmVK0F5q+Hcd8J7RmQwJKp77ff6dYRo+JZ0zlfPr9pNiYkQ4Q+eH/8ddm8DtGnOI2uWUN1JLEIGJvJ7J3S6d+et7QUPgMIuvXlzJS7G0wZ0xNLMFE9lKl4ugSQH0zCuspFA4tirivbYc74FP+VsI9Y4ZWMb22txcq44C2++O9bxrWXPiAZ0iC4fPtqTyGXAqeQkW/kDjEc+insAF8p/MLfH+JnhH1dhPijRXCI3bD3Mj9w4yySwBAvPeqEv3CYX/FsXQoSZbbUaVv1+0RRgHUWGPsCurBAjo+TK2a936CLe7KfXm0TbflLLPbrbCOJABDJ2JGQ3LiurJ8HpPlL1Xz7xtUOlvLooh4VINAGlGq7Kp1Dkj26ZN4ZGcjisWIHTTfVcon1VzCSn5e5xnqplWyexYlQwjwu/taXYdbzG4CZV8ENI8ppEN6rqIhmAfob+dwr7wvitDx9T/AzPtXEw6z5wFSUUnexedb0uB9sQEOll9KBPbyi6z0vv1lIpHJ+CM9cUTJe45zPcarhvGwktmwJjtUq893VxmXah/UFCWMFm7xxet7dUSLMOVsS3byjq0Aru212Q9DaWccH1iKeeUrGgBiIB+TeqydwOOSbZYBAT+5KFPYZBdttEaIsFd5QfahEU8HFeiqRgwZI4tNnmYK2DpoxCZnQJtE0oEJvCyAqOIaOF2a8HP/iYzPc/JV6RHhZCnW12JvLwojAxcCq0rul3OV+q8JJBQrlQcdh/9+R+ZZjke7bYjUnQvG3FnlJl/jMoJvkfEALvr70GQID'},host: 'smtp.office365.com',port: 587,secure: false,
});// OAuth2 授权参数
const oauth2Config = {clientId: '21f97687-903e-4806-903f-7c3162f73cea',redirectUri: 'http://localhost:3000/oauth2/callback',scope: 'https://outlook.office.com/SMTP.Send offline_access',authUrl: 'https://login.microsoftonline.com/consumers/oauth2/v2.0/authorize',tokenUrl: 'https://login.microsoftonline.com/consumers/oauth2/v2.0/token'
};// 获取授权链接
app.get('/oauth2/authorize', (req, res) => {const params = querystring.stringify({client_id: oauth2Config.clientId,response_type: 'code',redirect_uri: oauth2Config.redirectUri,response_mode: 'query',scope: oauth2Config.scope,state: '12345' // 可自定义});const url = `${oauth2Config.authUrl}?${params}`;res.json({ url });
});// 处理授权回调，获取refresh_token
app.get('/oauth2/callback', async (req, res) => {const code = req.query.code;if (!code) return res.status(400).send('缺少code参数');try {const params = new URLSearchParams({client_id: oauth2Config.clientId,scope: oauth2Config.scope,code,redirect_uri: oauth2Config.redirectUri,grant_type: 'authorization_code',client_secret: 'Brp8Q~qBdngo.SLNfJbc83YgtPqnKnrgHuBq.c8f'});const tokenRes = await axios.post(oauth2Config.tokenUrl, params, {headers: { 'Content-Type': 'application/x-www-form-urlencoded' }});res.json({ refresh_token: tokenRes.data.refresh_token, access_token: tokenRes.data.access_token });} catch (err) {res.status(500).json({ error: err.message, detail: err.response?.data });}
});app.get('/send', async (req, res) => {const { to, subject, text } = req.query;try {let info = await transporter.sendMail({from: '"TaxPlus" <sdkflja_ggg@outlook.com>',to,subject,text});res.json({ success: true, messageId: info.messageId });} catch (err) {res.status(500).json({ success: false, error: err.message });}
});app.listen(3000, () => {console.log('邮件服务器已启动，端口3000');
});流程：
第一步、 用 node 执行这个 js 文件
访问 http://localhost:3000/oauth2/authorize 获取授权链接
复制链接到浏览器登录账号进行授权，等待回调：
拿到 refresh_token 和 access_token 后，复制粘贴至图中此处：
第二步：
访问 http://localhost:3000/send?to=to@example.com&subject=666&text=666 发送邮件
返回 messageId 就是成功了
主要是 OAuth2 的验证比较麻烦
Outlook邮箱开通发信服务及OAuth2验证开通参考下面这个帖子：
Outlook邮箱开通发信服务及OAuth2验证开通-CSDN博客
