Don’t miss the Workfront AMA: System Smarts & Strategic Starts! Ask your questions about keeping Workfront running smoothly, planning enhancements, reporting, or adoption, and get practical insights from Adobe experts.
I checked with support and the Outlook add-in should essentially download the email add upload it as an attachment when you move it into Workfront which would be the closest thing to have the "history" in Workfront. It wouldn't be able to add that information into the update stream though.
We had the same question when we implemented the Outlook add-in and were disappointed to learn that replies in Outlook don't automatically carry into the related object Updates feed in Workfront. That would be amazing, since it's hard to break people of the email-only communication habit. I'm not sure if this functionality has been suggested in the Idea Exchange but it should be!