Configuring Yahoo mail in Microsoft Outlook (2000 / 2003 /2007) or Outlook Express is quite troublesome.

First, you need to know this basic details:

• Incoming Mail (POP3) Server: pop.mail.yahoo.com (Use SSL, port: 995)
• Outgoing Mail (SMTP) Server: smtp.mail.yahoo.com (Use SSL, port: 465, use authentication)
• Account Name/Login Name: Your Yahoo! Mail ID (your email address without the "@yahoo.com")
• Email Address: Your Yahoo! Mail address (e.g., user@yahoo.com)
• Password: Your Yahoo! Mail password

Next thing to do is download and install YPOPS
http://ypopsemail.com/

Then, follow the directions for your version of outlook on
http://help.yahoo.com/l/us/yahoo/mail/original/mailplus/pop/index.html

If you have trouble with set up, check the YPOPS installation page for alternate set up instructions.
http://dbeusee.home.comcast.net/

Click on YPOPS link on the left.
Then Click on Configuring email clients towards the bottom.
Choose the appropriate link for your mail client.