Now you can use your Yahoo Mail to access all of your mailboxes, including third-party accounts. It’s easy to switch between mailboxes to send or read email.

Connect a mailbox
1. Mouse over the Settings menu and click More Settings.

2. Click Accounts.

3. Under Mail click Mailboxes and click on Add mailbox

4. Select your email service provider.
Note: To add another business email account, select Yahoo!.

5. Enter your email address and click Add mailbox.

6. Sign in to your email account.
Note: To add a business mail account, enter your full email address as the Yahoo ID.

7. Follow any additional instructions presented

8. Click Save.

Now you can switch between mailboxes by clicking them in the sidebar menu where your Inbox and Folders are listed.
Note: It can take a while for your added mail account to sync with your Yahoo Mail account.