Email opened/not tracking from nodejs nodemailer

Question

What I know

I want to implement the email opened/not tracking in one of my websites. after searching i found that email-opened/not tracking is done by

Answer 1

I am not 100% sure if what i am posting is the correct way to do it but i figured out a way to make it work. Since this post did not get any valid answer all this time and i see some people viewing it i am answering my own question

You cannot track the opening of email if you send the 1px pic along with email as attachments using node-mailer as it will automatically render and send the file along with mail.(no external call made to server = you cannot detect). Render HTML using node-mailer as you do generally and input a pic with source to a route in your server like shown below

Now you have no attachments in your node-mailer and the file is not sent along with email, but will be fetched to render when someone opens the email.

You can track who opened the email using the unique key in url.

P.S. Don't forget to send a (1x1)px img file back for the request. so that no 404 error occurs on the client side.