Microsoft updated exchange/mail clients post 2016 to use a thread-index value in the headers to determine a messages relationship to an existing Conversation. Prior to Outloook/Exchange 2016 the subject line matching was sufficient. Currently ALL outbound messages from Remedyforce do not include a Thread-Index value in the email headers. This causes every outbound message to fork/create new conversational threads, which is important for clients.
This screen capture shows Outlook 2016 in conversation view Searching for the subject of the record. Conversation view is essentially useless, because Remedyforce emails do not include a thread-index.
Additionally the actionhistory strips the headers from prior communications, not allowing reply to leverage the existing thread index
I escalated this issue to BMC Support Ref: Case 00683404 and this was confirmed to require an APEX dev solution.
"DEV confirmed the issue will be an idea as the code is not available in the Apex Class to capture and maintain the thread index on inbound email. "