First setup

1. Create a new Google Cloud project here.
2. Enable the Gmail API for the project.
3. Complete the steps for configuring the OAuth consent screen. Add the email address you want to send from as a test user.
4. Go to here, click Create Credentials -> OAuth client ID. Select "Desktop app" for Application type, choose a name and click Create.
5. Click OK, a file will be downloaded. Move the file next to the program and rename it to credentials.json.
6. Install dependencies using python3 -m pip install -r requirements.txt.
7. Edit config.py and set the from_address properly.

Edit message_templates/header.html and message_templates/header.html to match your preferences.

Usage

Prepare a CSV file with a header row. It has to have a column named email.

Create a html template in message_templates for each batch of messages you want to send. In the template, you can use field names from the CSV inside curly braces({}). See the existing files for examples.

Then, invoke send_bulk_message.send_mail(subject, template_path, users_file, verify=True) to send the mail. If verify is True, the program shows a preview and waits for confirmation before sending the bulk emails.