What happens when I click on the mail icon on the main menu?

The mail icon on the main menu screen in the app takes you to your Notifications inbox. You must have an account and be logged in to view notifications. What are the in-app notifications for? You may receive notifications to alert you when other players add you to their friends list, invite you to play scheduled games, mention you in the forum, etc. Notifications may also be used to send alerts/updates from the game admin or to notify you of issues with your account.