From the Tools menu, select "Email Accounts."
Select the radio button next to "Add a new email account" and click the "Next" button.
Select the radio button next to "POP3" and click the "Next" button.
Enter the following information:
> Your Name: Enter your name as you'd like it to appear in the "From" field of your outgoing messages.
> Email Address: Enter your full Yahoo! Mail address (for example, "firstname.lastname@example.org").
> Incoming mail server (POP3): pop.mail.yahoo.com
> Outgoing mail server (SMTP): smtp.mail.yahoo.com
> User Name: Enter your Yahoo! ID (your email address without the "@yahoo.com").
> Password: Enter your Yahoo! password.
Do not check the box next to "Log on using Secure Password Authentication (SPA)."
Click the "More Settings" box and select the "Outgoing Server" tab.
Check the box next to "My outgoing server (SMTP) requires authentication."
Click the “Advanced” tab.
Under “Incoming Server (POP3)”, check the box next to “This server requires an encrypted connection (SSL)". The port number in the “Incoming Server (POP3)" field should automatically change from 110 to 995. If it doesn’t, make sure the port number is set to 995.
Under “Outgoing Server (SMTP)”, check the box next to “This server requires an encrypted connection (SSL). Enter port number “465” in the “Outgoing Server (SMTP)” field.
If you'd like to keep a copy of your email messages on the Yahoo! Mail server, click the "Advanced" tab. Check the box next to "Leave a copy of messages on the server." If you want to delete your messages from the Yahoo! Mail server after viewing them in Outlook, don't check the box.
Click the "OK" button.
Click the "Next" button on the Email Account Wizard, then click "Finished."