Set up your Spam Protection in Yahoo Mail.
1. Click on the "Options", Mail Options link in the upper right of your yahoo mail page.
2. Click on "Spam Protection", fill out the form and click the "Save Changes" link.
Once you have this set up, each time you see spam or mail that you want to block, check the box next to it, go to the top of the email list and click the "Spam" button, not the Delete button.
Note: Every message you report trains your Spam Guard filters to work better for you. The messages you select in this way will be deleted and reported as spam.
The senders of the messages will be added to your "Blocked Addresses" list.
PREVENT ACCESS TO YOUR ACCOUNT:
1. Change your password.
2. Clean your cache, delete history of visited websites and "Sign Out" of your account completely before leaving the computer. Click the "Sign Out" button.
If you leave it open, anyone can open and read your email. They can also go to the history function, or just hit the back button and get into your account.
Don't forget your ID and password though. You will need it the next time you sign into your Yahoo account.