To forward all of the messages sent to your Yahoo! Business Email to another email address:
Mail Options Menu: POP and Forwarding
On the POP & Forwarding page, click the radio button next to the "Forward Yahoo! Mail to another email address:" option.
POP and Forwarding: POP Radio Button
Note: You cannot forward your mail to another address and use POP at the same time. If you have turned on forwarding, and try to set up POP, you will receive an error. To begin using POP with your email, deactivate mail forwarding.
Enter the email address to which you'd like to forward your Yahoo! Business Email and select the forwarding behavior from the pull-down menu.
POP and Forwarding: Forwarding Address and Behavior Pull-Down
Click the Save button at the top of the page to save your changes.
POP and Forwarding: Forwarding Save Button
POP and Forwarding: Verify Forwarding Address Message
Keep in mind that when you forward all of your mail to another email address, new messages will not appear in your Yahoo! Business Email mailbox. (Messages received prior to enabling email forwarding will remain in your mailbox.)