Package gmail allows you to send email messages using Google GMail. You need to register the app on the Google server and get the configuration file that will be used for authorization. When you first initialize the application in the console will display the URL you need to go and get the authorization code. This code must be entered in response to the application and execution will continue. This function must be performed once the authorization keys stored in files. 1. Use wizard <https://console.developers.google.com/start/api?id=gmail> to create or select a project in the Google Developers Console and automatically turn on the API. Click Continue, then Go to credentials. 2. On the Add credentials to your project page, click the Cancel button. 3. At the top of the page, select the OAuth consent screen tab. Select an Email address, enter a Product name if not already set, and click the Save button. 4. Select the Credentials tab, click the Create credentials button and select OAuth client ID. 5. Select the application type Other, enter the name "Gmail API", and click the Create button. 6. Click OK to dismiss the resulting dialog. 7. Click the Download JSON button to the right of the client ID. 8. Move this file to your working directory and rename it client_secret.json.