You need to check your account’s POP3 configuration in outlook to make sure you are using the correct server and port (information that is provided by Yahoo in this case).
Also, make sure that you are using the correct user name and password.
If everything seems to be Ok, you might want to contact Yahoo support.
Check your mail server inbound and outbound settings in your outloook and make sure you have them set correctly.
If u can, please try out this….
1. From the Tools menu, choose Account Settings
2. Select the E-mail tab
3. Select ur Yahoo Mail account and click Change
4. Click on the Outgoing Server tab
5. Check the box next to My Server Requires Authentication
6. Please make sure that Log on using is not checked.
7. Click OK.
NOTE: The setting ur email client to remove messages from the server will cause ur messages to be deleted from the server. Once the messages are deleted, U are unable to retrieve them.
6. Click OK.
7. Close Microsoft Outlook and restart.
I strongly recommend that u enable SSL for both POP3 and SMTP (if u use), as detailed in the above instructions. This will ensure that ur Yahoo ID, password and email messages are transmitted securely between ur mail client and the Yahoo servers.