I logged into my Yahoo! Mail account the other day and was presented with the option to test their new interface. Overall, Yahoo! Mail Beta is pleasant to use and feels like a regular desktop client such as Outlook or Thunderbird. You can read RSS feeds alongside your mail and have the option of forwarding stories to your friends. You can also drag and drop email messages between folders without refreshing the page, thanks to a lot of AJAXy goodness. You have the option of using a preview pane for messages or a handy tabbed interface.
Yahoo! Mail Beta
However, the big disappointment would have to be speed. There are noticable delays when you attempt to load a folder and sometimes even when you select a message. Both Firefox and Internet Explorer stall when I attempt these basic tasks. However, it’s still faster than the old method of refreshing the page.

Almost two years ago, Yahoo! acquired Oddpost, which is now powering Yahoo! Mail Beta. Integrating two existing pieces of software can take much longer that it would first appear. Even after a lot of effort, the results can still be less than ideal. When time is limited, it is essential to decide early on exactly how far you want to take software integration. Otherwise, you could just get stuck waiting for your mail to load.