I've used FOXMAIL for many many years (I stopped updating at version 5), it was one of the first to employ a 'remote' viewer whereby you can view the mail waiting on the server, delete the cr*p and only download the legit stuff.
FOXMAIL has tons of features ( most I don't use) but the best being that once installed, you can copy the entire Foxmail folder to a USB stick and run it from that as everything is contained in it's own folder. So moving your email, contacts and account settings is a piece of cake.

FOXMAIL is used for all my business mail, while for personal mail I use Gmail which now, since Google Chrome, I run as an application window.