The checkbox's triumphant return is testament to the mistakes designers often make when they cater to their power users. It also shows the need for applications to focus on simple, visual, and adaptive (as in "single click") controls. Before they added back in the CheckBox you could still select multiple messages by holding the Ctrl key or select all messages by pressing Ctrl-A, but these shortcuts were difficult to communicate to anyone but the power desktop user. The checkbox, however, is easy to understand.

The other cool thing about the checkbox (and a reason why it could be a cool addition even to desktop mail clients) is that it lets you interact with multiple messages or select all messages using only your mouse. Trying to explain to your Grandmother that she needs to hold a key on her keyboard while carefully clicking on each message is neigh on impossible, it is easier for her to just move one message at a time. But give her a checkbox and she's in business! The checkbox makes organizing into folders much more accessible to all users, power or otherwise.

This brings us to the other old-is-new feature recently added back to Yahoo Mail: the move button. Again, you can move messages just by dragging and dropping, but that requires a precise (i.e. difficult) series of mouse moves that make the application less than accessible. By adding back the checkbox and the move button Yahoo Mail now has the power of a Web 2.0 mail client but the flexibility to be used just like a good old fashion "Hotmail inspired" mail client. Which just goes to show that the newest, flashiest, and most amazing features are nothing but liabilities if only 10% of your audience are comfortable using them.

Interested in doing more with Yahoo Mail? Check out our top 11 list of tips and tricks.

Yahoo's new version of web mail is, without a doubt, one of the coolest and most fluid Ajax applications we've seen to date. For the average user it offers every major feature that you can find in Outlook or Thunderbird, and it does it with style. But that isn't all, the Yahoo team also took the time to layer the app with embedded tricks, hacks, and shortcuts that makes the whole experience that much sweeter.

With that in mind, here are the top 11 tricks that I use everyday with the new Yahoo Mail Beta:

1. Trick: Instant Address Book Add - Drag a message onto the Contacts link and you'll see the icon change to a plus sign which means you can add that contact to your address book in one easy step.

2. Trick: Navigate your inbox the quick way - Ctrl + Shift + Up Arrow or Down Arrow let you jump to messages in the same folder that have the same subject line. You can hit Ctrl + Shift + Alt + Up Arrow lets you choose another factor to filter on (such as flag) when using Ctrl + Shift to navigate.

Yahoo! is rolling out an update to Yahoo! Mail Beta that combines Yahoo! Messenger with Yahoo! Mail. While this is a feature that Google's had for a while, I have to say, Yahoo!'s version looks pretty nice.

For example, when you start to write an email, the "To:" box will tell you if the contact you're writing to is online and available for chat. And if you've already started writing an email but have changed your mind and decided to initiate a chat, Yahoo! will automatically copy the text you've written into the chat window.

If you receive an instant message while you're working on an email or participating in a chat with someone else, a tab will pop up in the background, alerting you to an incoming message while letting you work in the current window. Ryan Kennedy of the Yahoo! Mail team has a screencast up demonstrating some of the new features.

Overall it looks pretty nifty. In general I've been pleased with Yahoo! Mail Beta. The interface feels much more like an application than a web page. But there's a price to pay. While the interface is definitely zippier now than when it first rolled out, it's still not as responsive as Gmail. Yahoo!'s in the process of rolling out the Messenger update and my account doesn't have the feature enabled yet, so I can't say whether it's as responsive in real life as it looks in Kennedy's screencast. If you've received the update let us know, and tell us about your experience with it.

Yesterday, Yahoo! announced the addition of some new features to the beta version of its mail app, which originally debuted earlier this year. Many of these new features are Firefox-centric. Improvements include:

• Integrated calendar at bottom of window
  
• File uploads/attachments take place in the background
• Addition of 'spam' column in message list, and return of 'size' column
• Firefox enhancements: faster composing, smoother scrolling, contact editing, no more overlapping search results (looks like they figured out how to clear floats!)

Been dying to try the new AJAXed-out Yahoo! Mail Beta? Well it turns out it only takes a few simple steps to switch your Yahoo! Mail account over to the new hotness. There's instructions over at the curiously-named Google Operating System, but they're a little vague, so here's the step-by-step:

1. Log into Yahoo! Mail and click on "My Account" and enter your password if prompted.
2. On the Account Info page next to the "Member Information" header click on "Edit."
   
3. Under "General Preferences" click on the link next to "Language & Content" or "Preferred Content" (mine says "Yahoo! U.S.").
   
4. On the subsequent page in the "New Setting" box choose Yahoo! United Kingdom, Germany, or France.
5. Click "Finished" and then "Finished" again on the next page.
6. You'll be prompted to sign a new TOS and then you should get an offer to join the Yahoo! Mail Beta.
   

Once you've joined, the setting will stick, so you can go back to "My Account" and switch your Language & Content setting back to whatever it was before. If you decide you don't like it, click on the "Switch Back" link at the top. As usual, your results may vary and there's no telling if and when Yahoo! will pull the plug on this particular trick.

Once again, Greasemonkey does not fail to amaze. Vivek Jishtu has written AJAX for Yahoo! Mail, a Greasemonkey user script (or stand-alone Firefox extension, take your pick) which, in case you hadn't guessed, adds fancy AJAX features to Yahoo! Mail, including message previews and "instant reply." This, at least, will do a bit to fill the Gmail gap while Yahoo! Mail users wait for the next version of Yahoo! Mail and its Oddpost-inherited features.