This plugin connects to the Gmail atom feed (https://mail.google.com/mail/feed/atom) and checks for new mail.

How to start using it:
1. Configure settings in the config file 'GmailPluginNotifier.conf.json'. Be sure to specify GmailUsername.
2. Execute the TrayPanels.exe. In the open window follow the instruction to obtain an access token.
Don't be scared about the access rights. The plugin uses only read access and keeps access tokens encrypted.
At the moment there are no other solutions for accessing to the readonly gmail atom feed, see this post:
https://productforums.google.com/forum/#!topicsearchin/gmail/atom$20feed$20readonly%7Csort:relevance/gmail/ygZFHw-cPg0

How to stop GmailPluginNotifier's access to your mailbox: 
1. Open https://security.google.com/settings/security/permissions in a Web Browser.
2. Logon to the google account of your mailbox.
3. Find the GmailPluginNotifier and deny access for it.