Yahoo was recently revealed was hacked into as was Netflix and EBay. Weebly recently became aware that an unauthorized party obtained email addresses and/or usernames, IP addresses and encrypted (bcrypt hashed) passwords for a large number of customers. For the site to check Google “Has my password been hacked” to get https://haveibeenpwned.com/. Change your password or consider ending your account. If you reuse your password for other accounts or in the past hackers use it. Change your password or possibly end the account. Use an e-mail that has a 2 step system, meaning you have to give your phone number or similar and will get a text if something is suspicious like being used from another computer. Use a password manager.
Cyberattacks disrupt Amazon, EBay, and Facebook and two other Bay Area sites, Google and Reddit, also had similar issues. http://abc7news.com/technology/cyberattacks-disrupt-access-to-facebook-twitter-netflix/1567318/
Recognize and secure a hacked Yahoo Mail account.
Yahoo hacking — what you need to know