Recently made the switch from paper & pen to Artful Agenda. It's available as a desktop & mobile app and is great for managing multiple calendars (it syncs with Gmail, Outlook, etc.). It's like a planner but interactive and can ping you with reminders. Plus, you can customize the fonts, colors, and decor if that is of interest to anyone!
Hi Tina! My current executive manages his own email, but he uses a folder system: "needs attention," "to be quoted," "articles," etc. Perhaps you can try doing that with your executive so this way the inbox will have less clutter, and what needs attention can be easily identified? After it is addressed you can either move it to its proper folder or move it to a "completed" one? Hope that helps or at least gives you some ideas to make things easier!