Part of my feed reading this morning lead me to sign up with Yahoo! Mail so that I could test out their new beta mail product. So I signed up with a Yahoo! NZ address of email@example.com but this didn't allow me to switch over to the new beta. I changed my location to UK, and noticed the link to test out the new Mail beta.
The beta is seriously cool, and makes Windows Live Mail look like the project of a pre-school coder. The interface is the closest to a full desktop application that I've seen for a while (the pre-alpha Roundcube Mail is similar to this too.) Everything is snappy – changing between mail folders, or opening and closing emails all happens quickly with no visible signs of waiting. Compare this to the constant "working on your request" messages you get while using Windows Live Mail (not to mention the "Windows Live Mail wasn't able to complete this request" messages with WLM too!)
There's also a snazzy button that lets you add a contact to your addressbook with one click from an email you've received. This won't make me switch email addresses as I still prefer the simpler, quicker interface you get with Gmail, but this is definitely a big contender for top dog in the email contests. Both Gmail and Yahoo! Mail put Microsoft's effort to shame. Let's hope that Microsoft takes a hard, long look at the competition out there and makes some big changes.