You can use Yahoo! Messenger from within Yahoo! Mail to send instant messages to contacts who are online and available. To send a message to a contact, please follow the steps below.

1. From the left side of the page, click the triangle to the left of "Online Contacts," and a list of your online contacts will appear. (Note: if you are signed out of Yahoo! Messenger in Mail, no contacts will appear. If you are not signed in, you can sign in automatically by clicking the lightning bolt icon next to "Online Contacts.")
2. Click on the contact you would like to IM, and an IM window will appear in the lower right corner of the page.
3. Enter a message into the text entry box, and then press the Enter key.

Please note that by default, you are signed in to Yahoo! Messenger from within Yahoo! Mail when you are signed in to Yahoo! Mail. However, if you sign out of Yahoo! Messenger from within Yahoo! Mail, this setting will be remembered the next time you sign in to Yahoo! Mail.