I think you could go back and ask a few more questions, like how long she's been getting these emails vs how long she's been in the system total. If she's been in there for a while, and is only just now getting these emails, you may be able to track the starting point to some related incident, like some sort of configuration to her user profile (addition to a team, for example). I'd also be asking who else it's happening to. (is it just her or Lexi as well?)
It's difficult to tell from the screenshots, but it kind of looks like they have two different distribution lists. Is the one at 10:07 only being sent to two people? And the one at 10:08 being sent to 9 people?
Lastly, Workfront has a tendency to place a link at the bottom of the majority of their emails, that says "Stop emails of this type" -- if you get this person to forward both those emails to you, you can click on both the links and see which type of notification is sending each email. If it's the same notification "type", and if this is consistently happening to a number of users, it might be worth submitting a case to Support to see if there's something going on that they can check on their side.