Registering Application in Google Cloud Console
To register an application in the Google Cloud console, do the following:
- Sign in to the Google Cloud console under a Google account that you want to use for sending emails.
 - Create a new project and enable Gmail API for the project.
 
You can do this with the Google setup tool.
- Configure OAuth consent screen for your project.
 - Create the OAuth 2.0 client ID credentials — a client ID and client secret for the custom application.
 - Record the following data required for acquiring an access token:
 
- Client ID
 - Client secret