1.In the upper-right corner of your Yahoo! Mail page, click the Options link, then select Mail Options from the menu.
The Mail Options page opens.
2.Click the Spam link on the left.
The spam options open on the right side of the page. The Blocked Email Addresses area shows all the addresses and domains that you have currently blocked.
3.In the Add a blocked address box, type the email address you wish to block, then click the Add button.
Tip: To block email messages from an entire domain (for example, baddomain.com), type the domain in this box.
The address is added to on the list.
4.To remove or unblock an address or domain from your list, select the entry to remove, then click the Remove button.
The address or domain disappears from your list of blocked addresses.