Apple’s is the IMAP/POP email application included with every Mac.

This application is a simple to use and easy to set up alternative to less functional web interfaces and more complicated email applications such as Thunderbird or Entourage. On the whole I would give a very positive review. The newest version, included in Mac OS X 10.5 Leopard, adds some great new features. Automatic setup means that if you use a popular service like Gmail or Hotmail or Yahoo, all you need to set it up is a username and password. Another excellent feature is basic RSS feed aggregation. It is a very simple implementation, less powerful than apps like NetNewsWire, but it is dead simple to use. The only negatives to are these two things: it only runs on Mac and it’s shutdown behavior is not standard. What this means is that if is busy (for example, trying to talk to a server that isn’t responding) it may block you from logging off or shutting down, requiring you to wait or force-quit the app. Despite this shortcoming, I fully recommend to any Mac user looking to make the transition from web-based email clients.