This sample shows how to send a confirmation emails to users who are subscribing/un-subscribing to a newsletter.

See file functions/index.js for the email sending code.

Sending emails is performed using nodemailer a node based Email client with comprehensive EMail server setup. For simplicity, in this sample we're showing how to send email through SMTP using a Gmail account. Be aware that Gmail has an email sending quota. If you are planning on sending a large number of emails you should use a professional email sending platform such as Sendgrid, Mailjet or Mailgun.

The dependencies are listed in functions/package.json.

When a signed-in user subscribes or unsubscribes to the mailing list we change the subscribedToMailingList boolean:

/functions-project-12345
    /users
        /$uid
            subscribedToMailingList: true,
            email: "user@domain.com"

Then the email stored here is used by the function to send the email.

The function triggers on changes to /users/$uid and exits if there are no changes to subscribedToMailingList.

Set the gmail.email and gmail.password Google Cloud environment variables to match the email and password of the Gmail account used to send emails. For this use:

firebase functions:config:set gmail.email="myusername@gmail.com" gmail.password="secretpassword"

This sample comes with a web-based UI for testing the function. To set it up:

• Create a Firebase Project using the Firebase Developer Console
• Enable Google Provider in the Auth section
• Import and configure Firebase in the public/index.html where the TODO is located

This sample comes with a web-based UI for testing the function. To test it out:

• Deploy your project using firebase deploy
• Open the app using firebase open, Sign in using Google Sign-In and subscribe/unsubscribe to the newsletter and you should receive email confirmations