nothingx

Did he use the information obtained to do anything illegal? Was there a loss of money involved? Unless you can find something like that, no, there is nothing that can be done. Email is insecure. Anyone listening to the network at the right time can see anything you send over email. Admins that run Yahoo can read her email.

Tell her to change her password, maybe even get a new email address. If her business needs privacy, concider using encryption or other means of communication.

By the way, its somewhat difficult to "hack" a Yahoo password. She probably gave her password to him and forgot about it, or didn't realize it. Might not have been a problem if she changed it every month like she should've.