I believe "Windows Live Mail" is an application. It's kind of like a really weak version of Outlook that comes with Windows for folks that don't have Outlook.
Her PC has an IP address, but the mail is probably not appearing to come from her local IP but from the IP of her mail carrier's SMTP server.
Just for instance, if you had an email address from a fictitious company named Qoogle, and your email address was "bob@Qmail.com"
The application (Windows Live mail) on your PC would connect to a server that might be named "smtp.Qmail.com." It would tell that server, I want to send the following message to
Sue@couldmark.com." Assuming you have an account on the smtp.Qmail.com server, it would then send your email to a server at the far end, maybe incomingmail.couldmark.com.
Sue@couldmark.com would then have her application connect to incomingmail.couldmark.com and say "do I have any new mail" to which the server would respond, "Yes, you have a message from "Bob@Qmail.com," here's the message.
I don't think that incomingmail.couldmark.com is going to see Bob's PC's IP address. It's going to see the IP address of SMTP.Qmail.com.
My guess is that they go an influx of mail (legit or spam) not from your friend, but from her mail domain, and that's what caused the issue. Have her try again.
I'd say there's a 99% chance that your friend has a dynamic IP address. If she reboots, she'll probably get the same address again, but if she powers her Internet router down for a few hours or overnight, she'll get a new IP address the next time she turns it on. If there's a chance that the issue is due to her home IP address (really, probably her Internet router, not her PC), then that would "fix the glitch" as the Bob's would say.