Yahoo Mail has feature using which you can block email address if you do not want to receive any emails from that address. This can be done using the Yahoo Mail Options.
Click on the Options link and select Mail Options from the menu list
Click on the Spam tab available on the left hand side and navigate to Blocked Email Addresses section.
Enter the email address to be blocked in the Add a blocked address field and click on the Add button.
The address would now appear in the block addresses list box as shown below.
After the adding the all the blocked email addresses, click on the Save Changes button available on the top of the Mail Options screen.