When enabled, Smart Notifications is a setting that stops push notifications notifications when users are not rostered for the next event. The only notifications that users will receive are mentions. You can access the group chat anytime, but unless your @username or @group is used in the chat, you will not be notified.
Smart notifications active with the default settings for new account. Smart notifications will appear unset (grayed out with the toggle in the middle). Unset means that by default, smart notifications are on.
Users can set smart notifications on globally, meaning all group messages will use your master setting found by selecting your
User Profile → Settings →
Smart notifications should be the third option/toggle.
You can also set the smart notification settings for each group by selecting
Group Dropdown → Settings
Under the section "My settings" you will see the option/toggle to turn this on or off for each group.
*If there are no events upcoming in the group message, all users will be notified regardless of smart notification settings. This is because there is no event to determine the smart notifications.*