Opera Mail

Opera is primarily a browser, but is has features of an email Clint with it now. That means you can actually use a browser wit all its function – surfing, downloading and now even emails. You can setup and use multiple email accounts and even manage your folders like you were using an actual email Clint.
Setting up Opera Mail is quite easy as it supports POP3, IMAP and even IRC Chat. Emails can be categorized by labeling them with any of the seven labels available – Important, To do, Send Reply, call Back , Meeting, Funny and Valuable, each having their own distant icon. Emails can also be categories according to own distinct icon. Emails can also be categorized according to their attachment types such as documents, image, videos and movies. Opera Mail, being integrated with the browser, opens each email in a separate tab. You can also just highlight any text displayed in Opera, and just right-click and select a send by mail a new tab ones with your compose message screen.
Opera Mail initially just downloads the email titles, but you do have the option to download the mail bodies also. Opera as a whole is also customizable in terms of skin colours and themes.
Opera Mail also comes with a spam filter (which is Bayesian, and learns as it goes along) customizable rules, and as RSS and Atom feed reader.
Opera Mail is a good alternative to an email Clint, but you may probably use it only if you use Opera as you primary browser. Although we can’t really consider it an email Clint, or compare it to the others tested here, it’s impressive and easy enough to get honorable mentions.