Now you can talk to your contacts on Yahoo! Just add their e-mail addresses (like all your other Messenger contacts) and you can see if they're online or offline and even share emoticons.
From the menu, click Tools and select Edit My Mobile Settings.
Enter your information
From the Phone menu in the Options screen enter your phone numbers and click Allow people in my contacts list to send messages to my mobile device.
Click Mobile Settings
Click Mobile Settings and follow the instructions. Once completed, click OK. Your contacts can now send messages to your mobile device*. In addition, when you send a message to a mobile device, you can include your call back number.
Offline Messaging
Send a message to someone, even when they're away.