Spike is the perfect email client for teams. They turn email into a live-chat-like experience, which makes email more personal, more fun, easier to manage, and it helps me and my team get things done faster. On top of that, it's packed with team features - like built-in group chats, collaborative notes (with realtime editing and commenting), tasks and to-dos, and even audio and video calls. And it's all inside one app that is built really well, UX-wise.
It basically replaced a ton of other apps we were using internally to manage our team. A great find!