Ranked in these QuestionsQuestion Ranking
Pro A perfect companion to your Gmail or other webmail you might have.
Pro Beautiful interface, customisable to your needs
Pro Very fast
Pro Free and paid version
It is free for 2 accounts and as long as you don't use it commercially. Paid version comes with support and can handle more than 2 accounts.
Pro Calendar inclusive
Pro Chat included
eM Client includes integrated chat, so you don't need another application for chatting with your friends. All common chat services supported (Google chat, Jabber and others).