Owing an Email address means that you will always receive unwanted mails from all kinds of account. Fortunately, almost every email provider have the function to block some kinds of mails. Here introduces some common solutions to block emails on Yahoo mails.
Steps - How to Block Emails on Yahoo
If you've already received the mail, then you can open your mail account, tick off the mail in the mail list you want to block, click on the button "Spam" in the menu bar. This mail will be moved to "Spam" folder, so you won't see it in your Inbox.
You can also open the unwanted mail, then click on the button "Spam" in the menu bar for the same result.
If you have further requirement on blocking mails, then you can tick off the mail you want to block, click on the button "More" in the menu bar and select "Filter Emails Like This". Then you'll see the message box as follows. You can edit the filter rule to control the block, but remember to save the rule after you finish the editing. You can block an email from any sender, or block email containing specific keywords, and these blocked mails will be removed to Trash folder or other folders you create automatically.
If you haven't received the mail from the sender you want to block, you can also block it by taking following procedures. First, you need to open your mail account. Then move your mouse to top right corner to find the icon "gear", a menu will be showed, and select "Settings".
Choose "Blocked Addresses" in the left column, then you can input the mail address you want to block. After you finish the input, click on the button "Block", the mail will be blocked automatically. You can also remove the address at any time.