You have an incorrectly set up account.
However, you have not provided any where enough information for us to help
you.
Who is your ISP?
Have you contacted them for help setting up your mail account?
Are you trying to use the "free" yahoo in Windows Mail?
What was the exact wording of the error message?
What is the color of your hair?
Right-click on the error message, copy, then paste it into a reply here.
We can't do much with just a small part of the error message.
Are you trying to set up a Yahoo account in Windows Mail?
US-based free Yahoo accounts have webmail access only, no POP
access. Windows Mail does not handle webmail.
There are three possible solutions:
1. How did you access Yahoo mail before? If you are happy with
webmail via your browser, you can continue to use that.