Help me, e-mail virus?

[Rob]

My mother asked me to create a new hotmail account for her, just for her work, and I gladly did so. When we came back to the old e-mail, however, we were startled to see a message that read someone may had known our password, and that we needed to send our cellphone number blah blah blah and we did so. We got the code, we input it, and BOOM we're in the inbox.

Now HERE's the issue. We're greeted to see 29 Delivery Status Notification (Failure) messages, marked with the timestamp ranging from 17:43 to 17:36. All the supposed sent messages (my mother hadn't used her email today) were composed of a link, never the same in each message, that read a random website, followed by /twitter, or /facebook, or /foxnews, basically well known websites, and ended in .htm

My assumption was a virus or a hacker got into her email. Question is how. She never gave away her password, she did not visit her email today, let alone in that hour, so how could she have visited a website for it to hack her email?

I'm trying to understand what is going on, what's the source of this and what can I do to fix it. Any additional data I'll be happy to give.
*17:43 to 17:46
Apparently she was yesterday searching for her thesis and she came across a fromdoctopdf (dot) com download advertisement. Could this be it? (from people who know what's in there)

[Taco Dance]

Not to worry, this is common. The email acocunt has been hacked. The resolution is to change the password. It sounds as if this has already been done. So your ok.

What happend is, simply somebody(program) got your password and sent an email to everybody in your moms contact list. I would fallow up with those people to let them know youve been hacked, incase the message contained a virus. But it was likely just an ad for some stupid thing.

So, again all that needs to be done is change the password.