Email Client (home use)
Currently I recommend 'Mozilla Thunderbird' to home users, specifically with the 'Lightning' extension installed (to provide calendaring functions).
As you can see from the image on the right, Thunderbird is also capable of accessing multiple email accounts simultaniously without sending all incoming mail to a single inbox in the way that most other email clients do.
I prefer my customers to use Thunderbird because I am very familiar with it which makes offering telephone support much easier.
Mozilla Thunderbird is free software.
You can find Thunderbird here:
http://www.mozillamessaging.com/en-US/thunderbird/
and you can find the Lightning extension here: