nodemailer eg

index.js

const express = require("express");
const bodyParser = require("body-parser");
const mysql = require("mysql"); //as we use a MySQL database
const nodemailer = require("nodemailer"); //to send mails
var cors = require("cors");

const Server = "aqueous-refuge-02128.herokuapp.com";

const app = express();
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.use(cors());

var conn = mysql.createConnection({
    host: "ssdfsdfql6.fsdfsreefsdfmyfsdfsdssdfsdqlfsdfsdhosdfssdfsdting.net",
    user: "sqsdfsdl6sdf467dsf324471",
    password: "A2342bsn23Mv3l4p7",
    database: "sql6234325234467471",
});

var transporter = nodemailer.createTransport({
    service: "gmail",
    auth: {
        user: "abc@gmail.com",
        pass: "3asdfasdf33asdfsdf1sdfas11sdfsdf1120",
    },
});

app.listen(process.env.PORT || 5000, () => {
    console.log("Server is listening...url: " + Server);
});

app.get("/", (req, res) => {
    res.json({
        message: "Hi this is mail tracker node server",
        url: Server,
    });
});

app.route("/sendmail").post((req, res) => {
    let Sender = req.body["Sender"];
    let Recipient = req.body["Recipient"];
    let MessageBody = req.body["MessageBody"];
    let Subject = req.body["Subject"];

    let htmlBody =
        "<p>" +
        MessageBody +
        "</p>" +
        '<img src = "' +
        "https://" +
        Server +
        "/recipients/" +
        Recipient +
        '" style="display:none">';
    var mailOptions = {
        from: Sender,
        to: Recipient,
        subject: Subject,
        html: htmlBody,
    };
    transporter.sendMail(mailOptions, function (error, info) {
        if (error) {
            console.log(error);
        } else {
            conn.query(
                "INSERT INTO recipients(email)  VALUES(?)",
                [Recipient],
                (err, rows) => {
                    if (err) {
                        throw (err, console.log(err));
                    } else {
                        res.send({ status: "success" });
                    }
                }
            );
        }
    });
});

app.route("/recipients/:recipient").get((req, res) => {
    var Recipient = req.params["recipient"];
    var date_ob = new Date().toISOString().slice(0, 19).replace("T", " ");
    conn.query(
        "UPDATE recipients SET opened = true, lastseen= ? WHERE email=?",
        [date_ob, Recipient],
        (err, rows) => {
            if (err) {
                console.log(err);
            } else {
                console.log("Data Inserted:");
                res.send({ status: "success" });
            }
        }
    );
    res.send({ time: date_ob });
});