How to block someone on Yahoo mail?

Sign into your yahoo mail.
Click on “Options” which you can find on the top right hand side of the page.
Under “Spam” heading you can find a link called “Block Addresses” click on this.
In the text box enter the email address or the domain name and click on the “Add Block” button.
For example
someone@someone.com – email address
someone.com – domain name
Once you do this the mails will be blocked and you will not receive any mails from the blocked address.

All the best!