The new Yahoo Mail Beta is touted as being as functional as a desktop email client, such as Outlook. It has tabs, so you can compose mail, search and read mail in the same window. Every view shows the entire list of mail, so you don't have to click "Next" multiple times until you find a message. The window has a preview pane so you don't have to open each mail. The contact list is slick, it has an instant search feature, but you don't have use it when composing messages because Yahoo autocompletes email addresses. The feed reader doesn't have an import option yet, but it looks nice: you can customize the font and text size, forward posts, so reading feeds is more pleasant than reading mail.
Because Yahoo's users are more conservative, the new Yahoo Mail doesn't include mail threading, so you can read conversations in context and it still uses folders instead of labels. Search is almost inexistent: there's no advanced search so you can't search for that important mail sent to you in June, there's no word matching so if you search for "cop" you'll find "copy", "copyright", "Copenhagen". There's no preview for attached documents and the settings section looks the same as last year (ugly and cluttered).
Ethan Diamond, director of product management “Yahoo! Mail”, in an interview with Richard MacManus of readwriteweb —”Yahoo! Mail is the No. 1 Web mail service in the world - it has 255 million users according to comScore's July 2006 figures. By comparision, MSN Hotmail has 234 million, AOL Mail 56 million and Google's Gmail 49 million.”