When I first started using email it was from a Mac Plus connected through the work server. In those days Eudora was free and the best emailer going on the Mac. Since then I have changed machines many times but Eudora is still free, available for both Windoze and Macs and allows me to keep all my messages organised the way I want and on my own machine so, despite the blandishments from other suppliers, it's the program of choice for me. It also doesn't do things in the background unless I tell it to, unlike some others.

Cheers, Rowan