Highlight the message in your Inbox by clicking on it or in the check-box beside it. Then click Spam.

Also, make sure you're blocking images. Why? Because when images open in spam emails, they can confirm your email address to the spammer. So, here's how to block 'em:

1. Click Options in the upper-right corner of your Mail page and select Mail Options.
2. From the list on the left, click Spam.
3. In the SpamGuard section, find Show incoming images;.
4. The most secure setting is "Initially block all images". But you can choose to view some images from known senders, or to show all images, if you'd like.
5. Click Save Changes at the top of the page.

We pay a lot of attention to spam you report to us. It gives us tools to disrupt the latest tricks and techniques that spammers are using, and helps us fight spam more effectively.

Spam originating from a Yahoo! Mail account (i.e., user@yahoo.com) gets special attention. If you receive spam sent from a Yahoo! Mail account, please send us an unedited copy of the message with full headers via our Mail Abuse Feedback Form. Since spamming is expressly prohibited in Yahoo!'s Terms of Service, any account caught spamming will be canceled.

If you change your mind or think you made a mistake, just look for the next message from that sender in your Spam folder and click Not Spam.