Yes, Yahoo! Business Email offers the following ways to help you block junk mail:
If you receive multiple messages from the same source and would like to block the sender, you can set up a filter to match some unique part of the sender's address. Generally a name or a phrase in the body of the message works well, but as long as the sender always uses the same mailing address, filtering based on the Sender: field is very effective. Just set the destination folder to Trash.
Note: Using filters to avoid unwanted mail doesn't actually prevent it from being sent.You can also use the "Blocked Addresses" feature to automatically delete a sender's messages.
Mail Options Menu: Blocked Addresses
Blocked Addresses: Add an Address
Yahoo! Business Email allows up to 500 blocked email addresses. Learn more about avoiding spam.