If you are concern about safety and security of your Yahoo Mail account; you need to increase the security using the advanced level of security. We have this quick guide for you.
Yahoo Account Key
You can enable at least any of these two securities on your Yahoo account and once you enable them; you can see the difference. Now, your account will need your permission to get in.
For More Details:- http://email-tips.com/yahoo-mail-alert-as-fast-as-it-gets