Try this please>, navigate to Options and then click Import email accounts. Select Yahoo, enter your Yahoo email address and password, and then click Import. This will also set up your Yahoo email address as a “send from” account, meaning you can continue to send emails from your Yahoo address, right from Outlook.com, also connect your Yahoo account to your Microsoft account, so your Yahoo appears in Outlook.com.
When you add your IMAP enabled account (such as Yahoo Mail) to Outlook.com you can continue to send and receive new email from your current address, and import your old email and calendar info. To add your account, follow these steps.
Run the import tool
Automatically forward your email to Outlook.com
Add your contacts
Import or subscribe to your calendar
Choose a "From" address
Sort incoming email into folders
The import tool will import your existing email messages and set up Outlook.com so you can send email from your IMAP enabled account address. Run the import tool and follow the instructions on your screen. When you're done, come back to this page to finish the other steps.
Run the import tool for Yahoo
Run the import tool for other IMAP accounts
Here are instructions for Yahoo Mail on the Yahoo! website.
To set auto-forwarding for other IMAP accounts, see your service provider's support section.
If you have a Yahoo account, you can import the contact list to the People web service in Outlook.com. If you have another email service, you might be able to connect your contact list.