To enhance productivity and streamline task management, adding a Notes and To-Do List feature alongside the existing Contacts, Calendar, and Security Center on the right side of the interface would be great additions to the Proton Mail environment. These would make it possible to quickly jot down notes and manage tasks without needing to leave the workspace. The integration would provide easy, on-the-go access to important reminders, and a help to stay organized and on track, all within the same environment.