And this is my first attempt to write a tutorial...
In case you're configuring from scratch, you need to install sendgrid plugin, otherwise its already included in the tgz file.
To install the plugin:
npm install --save @sendgrid/mail
The index.js includes 2 options to send an email.
If you want to use the first option. Simple email, then uncomment before //Use this method to send regular email and comment before //Use this method to send email with dynamic template
There are no additional configurations to be done.
If you want to send an email with a dynamic template(customized), the second(default) option then first you need to create the template via the sendgrid UI: