I'm on the Engineering team that works on Citrix Files for Outlook (formerly ShareFile Outlook Plug-in).
I'm afraid I've read over your post a number of times and I'm not sure what you're asking for. Are you talking about wanting conversation history to display inside of Outlook, or showing up elsewhere after you've sent an Encrypted Email through Outlook?
When a user replied to an Encrypted Email and it decrypts for you (if you're authenticated into the same account as them) then you should see the conversation history in your email thread. Is this not what you're seeing?