If you receive multiple messages from the same source and would like to block the sender, you can set up a blocker to match the sender's address or entire domain. As long as the sender always uses the same mailing address or domain, blocking based on the "From" field is very effective.

To block an address: 1. From the upper-right corner of your Inbox page, click "Mail Options." 2. From the list of mail options, click "Block Address." 3. Enter the email address or the domain name you wish to block. 4. Click "Add Block" to save it in your list of blocked addresses

If you would like to automatically block the senders of messages you mark as Spam, you can choose this option in the Spam Protection section of the Mail Options page. You can block 500 email addresses and/or domains with Yahoo! Mail.