I have been using Nodemailer for a few personal and commercial projects to send email from Node.js

It has been working quite fine even with Gmail. However now my Raspberry Pi memory card broke (again) and I decided to move a personal project from it to my Hetzner server.

The email sending feature had worked nicely for a long time but after trying to setup the system to my Ubuntu server, the email sending didn’t work. It always faulted to a timeout error:

Error: Connection timeout
    at SMTPConnection._formatError (xxx/node_modules/nodemailer/lib/smtp-connection/index.js:790:19)
    at SMTPConnection._onError (xxx/node_modules/nodemailer/lib/smtp-connection/index.js:776:20)
    at Timeout.<anonymous> (xxx/node_modules/nodemailer/lib/smtp-connection/index.js:235:22)
    at listOnTimeout (node:internal/timers:564:17)
    at process.processTimers (node:internal/timers:507:7) {
  code: 'ETIMEDOUT',
  command: 'CONN'
}

The old code used directly the available service: 'gmail' transport setting:

Non-working solution:

const transporter = nodemailer.createTransport({
  service: 'gmail',
  auth: {
    user: settings.notification_email_address,
    pass: settings.notification_email_password
  }
})

//Create mail settings
const options = {...}

//Send 
const res = await transporter.sendMail(options);

I tried to find a solution to this problem for a while. Finally after testing many things, such as opening ports or disabling firewall, this quite new StackOverflow answer helped!

For some reason, everything works fine when using SMTP settings instead of Gmail service. The following example does the trick on my Ubuntu server:

Working solution:

const transporter = nodemailer.createTransport({
  host: "smtp.gmail.com",
  port: 587,
  secure: false,
  requireTLS: true,
  auth: {
    user: settings.notification_email_address,
    pass: settings.notification_email_password
  }
})

//Create mail settings
const options = {...}

//Send 
const res = await transporter.sendMail(options);

Hopefully this helps somebody!