User blog comment:BertH/Introducing Announcements, a new way to notify your community/@comment-25295528-20180717161302/@comment-5275700-20180717191126

The older system is the one used for Message Wall and Forum notifications, and it has some bugs. The newer system (shown under the 'bell' icon) is, up to now, only bene used for Discussions. It's much more stable and also displays for mobile users.