This is a big problem for us. A customer's reply to an ongoing support thread will create a new ticket, instead of being added to the original thread. It seems to happen in about 1 out of every 10 tickets. We've been searching all these orphaned responses for some kind of pattern. At first we thought maybe it was happening because the customers were responding from a different email address. But no -- we verified that at least some of these orphaned responses definitely came from the same email address that was used to create the original ticket. And the original threads were definitely "Open" or "Waiting for reply" when the response came in.
So at this point, we're kind of at a dead end. How can we stop this from happening? It's becoming a bigger problem as our company grows and we have to train new support people.