How to send the email using the firebase for the transections

Using Trigger Email from Firestore

How this extension works

Use this extension to render and send emails that contain the information from documents added to a specified Cloud Firestore collection.

Adding a document triggers this extension to send an email built from the document’s fields. The document’s top-level fields specify the email sender and recipients, including to, cc, and bcc options (each supporting UIDs). The document’s message field specifies the other email elements, like subject line and email body (either plaintext or HTML)

Here’s a basic example document write that would trigger this extension:

admin.firestore().collection('mail').add({
  to: 'someone@example.com',
  message: {
    subject: 'Hello from Firebase!',
    html: 'This is an <code>HTML</code> email body.',
  },
})

You can also optionally configure this extension to render emails using Handlebar templates. Each template is a document stored in a Cloud Firestore collection.

When you configure this extension, you’ll need to supply your SMTP credentials for mail delivery. Note that this extension is for use with bulk email service providers, like SendGrid, Mailgun, etc.