Mail arrives from a customer Read and sorted four questions Needs a reply? yes Waits in Pending reply the waiting time is shown, and grows no Counted, then left alone nothing for you to do someone answers Moves to Replied leaves the pending pile How it knows an answer was sent The system watches the conversation, not the send button. When a newer message appears in the same conversation, it treats the earlier one as answered. That check runs with the next collection round, so a reply you have just sent can take a few minutes to leave the pending pile.