As you know, when your email address already targeted by spam sender, they will always spam your inbox with forward email, advertising, scam and other email that against the ethics. In Yahoo Mail, there is an option where you can block certain sender from sending an e-mail to your account. To do that, just follow this simple step:

First, login to your Yahoo Mail account. Go to your email option that located below the "web search" button on the right side of your email. On the drop down menu, please choose "More Options...". On the left side bar, there are your option setting menu and proceed to "Spam" link settings. In the spam setting windows, there is a portion called "Blocked Email Addresses", you can add up to 500 list of your blacklist email account into that list by clicking "Add" button or you can "Remove" it anytime.

Now, Yahoo Mail will totally block all the email that sent by your black listed email address. With this tips, you actually can reduce the number of spam in your inbox and thanks to Yahoo Mail for this option.