@[deleted], don't know if this will help in your case, but we saw the same when forwarding messages from one osTicket instance to another. The problem is the Reply Separator Tag is the same at both ends, so the sender forwards the message starting with "-- reply above this line --", and the receiver splits the incoming message to take only what is above that line, ie. nothing, hence the empty message seen in the ticket.We solved this by adding a UUID to the end of the separator tag in osTicket, so it's still readable, but now globally unique. Even if your sender is external, this should still work just because they are different.Hope this helps.
