A, before i answer, did she click on a link in an email that she didn't understand. I wonder how the hackers get into the accounts? Some of them "force" their way in by using a program to test thousands of passwords. But it takes a lot of effort and they don't get much in return (in most cases). As far as proving her identity, Yahoo used to allow her to fax her drivers license to prove her identity. When Yahoo hit 500 million accounts, they automated everything. Which is great until someone in Russia hacks your account and changes every possible option to get her back in. Right now, a hacked account has zero options. That may change since there is new ownership.
Slowness in Yahoo Mail is often due to problems with browsers. Go through each step and I'm sure you'll sort out the problem:
Hope that helps!
Sometimes when emails go missing it's because of another program or app the account is being accessed from. It may be set up to download emails from our server but not leave a copy of them, making it look like emails disappeared. Also, syncing issues between the account and a mail app can cause emails to be removed from our servers and be deleted or moved to the app/client instead. If you access the account through a mobile device or app, you may want to remove the account from the device and re-add it to resolve any syncing issues. If needed, you can request a Mail restore here. Keep in mind that the Sent, Spam, and Drafts folders can't be restored and any restored email will appear in the Trash folder.
This is something our engineers are currently investigating, including the cause. It appears to be triggering on mobile web browsers. Sorry for the inconvenience. We hope to have a solution soon.
For anyone noticing that this is no longer occurring for them, please do let us know.
Marking this post as a temporary "solution" for visibility.
Hi there, This is a current known issue that is affecting customers with inactive accounts. Please take a look at this post in the Known Issue board for updates on this issue. Thanks.
Please Note: This is only marked as the solution so that this answer can be seen if/when other customers review it.
I checked out the account and everything seems to be in order. I didn't see any error or issues in the mailbox. I would try clearing the cache in your browser and make sure you're using a supported web browser like Firefox or Chrome.