When Salesforce support sends me an email I can reply back to it and it appears in the case on their end (I assume--I've never seen there support system from their side).
I'm wondering why the emails I send from a case to a customer aren't similarly configured such that when the customer replies to it the message appears in the case's activity list.
In fact, the only reply-to information is my own email address.
What configuration option am I overlooking?