We have been installing eM Client for over 3 years on customer computers and laptops. It offers easy setup on both Windows and Mac OSX with an ad-free clear interface. This is helpful if you struggle with distracting information on screen, there are three themes so it is possble to choose something visually clear. The eM Client offers integration with your contacts and calendar, tasks and chat. It integrates with Google Mail (gmail), Yahoo, BT Internet, iCloud, Office365 and Microsoft Exchange.
I have chosen to be a reseller because my customers have successfully been using this software (which is free for 2 email addresses). The Pro version will provide unlimited email addresses, commercial use and access to VIP support. I am still happy to install the the basic version for users just looking for simple clear access to their email.