4. Zimbra Desktop
This is one the mail client I haven't tried myself, but Zimbra Desktop has a loyal following among business-minded usersand there's no reason it can't pitch in at home.
Indeed, as PC World's Jon Jacobi wrote in his Zimbra Desktop review, "Not only does this elegantly-styled program offer most of Outlook's features, it interfaces to social media sites and services: Facebook, Twitter, LinkedIn, WebEx and Digg currently."
Consequently, this might be the preferable choice for anyone making a move from Outlook.
Have you found what you consider to be the ultimate desktop email client? Tell me about it in the comments!
Contributing Editor Rick Broida writes about business and consumer technology. Ask for help with your PC hassles at firstname.lastname@example.org, or try the treasure trove of helpful folks in the PCWorld Forums. Sign up to have the Hassle-Free PC newsletter e-mailed to you each week.