I assume that to copy the email you're hitting reply or forward and just selecting all and copying.
If so, I see that Outlook is formatting the email header with manual line breaks, and the rest of the email with paragraph marks. We don't really have a lot of options in this kind of a case, since that's just how Outlook works (I suppose you can complain to microsoft).
1) You could try submitting a helpdesk ticket to say that Workfront updates is not reading or honoring the manual line breaks. The possible results here are:
a) they will decide it's a defect and fix it
b) they will decide it's working as designed and close your ticket. You can then post it as an "idea" and if it gets enough upvotes, you could get this changed.
2) The workarounds:
a) run a search and replace before you copy the email so that it replaces all the manual line breaks (^l) with paragraph breaks (^p). It could be a "find and replace all"... people who are more expert than me can maybe figure out a way to make it a macro so it only costs you a few more steps.
b) if you are on outlook 365, you could go to web: use https://outlook.office365.com/ for your email if you can. Doing the same copy/paste step in there, I see that the email headers are being translated to lines with paragraph breaks.
I highly recommend 2)b) if you can make it work for you, or if your IT can help you out.
Otherwise, I'd be willing to upvote an idea if you post it. Here's the link to post an idea: https://experienceleaguecommunities.adobe.com/t5/workfront-ideas/idb-p/workfront-ideas