Here is how the plugin uses the user data from the Google account:

1. The plugin periodically queries the contacts of the Google account

2. When the user uses the address completion feature in Claws Mail, the plugin adds the contacts from the Google account query to the results

3. When Claws Mail is shut down, the plugin stores the latest Google contacts information in a cache file in the Claws Mail config folder. This cache file is used when the application is started again until the first query to the Google servers could be performed.