You'd have setup a common reply template for agents under Admin -> Email notifications-> Reply template -> Agent reply template to reflect your branding. In a high volume environment, it's not always the ticket assigned agent who responds to the ticket. The agents can pick up tickets and reply on their own but there is one little problem here. In your common signature setup, you might have used the placeholder {{ticket.agent.name}} to populate the agent name. However, it would populate only the ticket assigned agent's name. What you'd probably need is a placeholder that detects the current replying user. This app does that for you - fetches the current user's name and inserts it onto the common reply template setup ,thus preventing the agent name mix-up