Our own @  is quoted here about being responsible for your security:

 

 

“In addition to multiple passwords, end users should also change their passwords on a regular basis and make sure to take advantage of any additional layers of security available such as biometrics, PIN and so on to ensure their data is safe in spite of any attempted hacks.”

 

Since many people use the same password everywhere, your users could have a home Yahoo account with the same password as their work accounts.  Good time to remind everyone to change their passwords or update your security policy to require regular changes.