SMTP ERROR using Nodemailer to send email

Question

i am building a web app and i want to send emails to registered users that forgot their password. But I am having problem with sending the mail through Node mail. I keep getting a 421 response error that the server is busy with too many connections ans i dont understand why.

below is my code and the error i keep getting.

require('dotenv').config()
const nodeMailer = require('nodemailer')


const sendMail = async (email, token) => {
    const transporter = nodeMailer.createTransport({
      host: process.env.EMAIL_HOST,
      port: 587,
      auth: {
        user: process.env.EMAIL_USER,
        pass: process.env.EMAIL_PASSWORD,
      },
    });
    console.log("passed transportrt ");
    await transporter.sendMail({
        from: process.env.EMAIL_USER,
        to: email,
        subject: "Password RESET",
        text: `Follow this link to reset your password. It expires in 15minutes. \n\n
         http://localhost:4000/reset/${token}`,
    });
    console.log('out') 
}

module.exports = sendMail

the other parts and work flow works well till it gets to await transporter.sendMail({... and this is the error i keep getting below

Error: Invalid greeting. response=421 Service not available: 421 Service not available
    at SMTPConnection._actionGreeting (.../node_modules/nodemailer/lib/smtp-connection/index.js:1205:27)
    at SMTPConnection._processResponse (.../node_modules/nodemailer/lib/smtp-connection/index.js:947:20)
    at SMTPConnection._onData (.../node_modules/nodemailer/lib/smtp-connection/index.js:749:14)
    at Socket.SMTPConnection._onSocketData (.../node_modules/nodemailer/lib/smtp-connection/index.js:189:44)
    at Socket.emit (node:events:526:28)
    at addChunk (node:internal/streams/readable:315:12)
    at readableAddChunk (node:internal/streams/readable:289:9)
    at Socket.Readable.push (node:internal/streams/readable:228:10)
    at TCP.onStreamRead (node:internal/stream_base_commons:190:23) {
  code: 'EPROTOCOL',
  response: '421 Service not available',
  responseCode: 421,
  command: 'CONN'
}

Is there something i am possibly doing wrong? Plus i am running this on unbuntu(if it has any connection to the error)

Answer 1

A 421 error with an EPROTOCOL error usually means the mail client could not connect to the mail server. Two easy possibilities to check:

• process.env.EMAIL_HOST is not defined (not set in .env file or OS)
• Your server cannot connect to the mail host at port 587 (easily checked with telnet).