Module guide: Incoming message
Start the action when somebody sends you a chat message
What it does
Use the trigger, Incoming message, to start the action path when you receive a chat message from someone visiting your website. To ensure high-quality customer support, you can send an automated message when you are out of the office so none of the messages are left without a response.
How to use it
Go to "Automations" -> "Create automation". From the menu on the right, drag and drop the trigger, "Incoming message", click on it and a window will appear like the one shown below: 
Decide what type of message this action should trigger: Chat/Email/API/SMS/Any. Set the timeout (meaning the number of seconds after the last message from the user before the action starts).
Case Study
Set the timeout (the number of minutes after the last message from the user before the action starts) then connect it to a condition, Agent responded. This way, you can check if, within a certain period of time, one of your agents has responded to the user. If not, connect it to Filters: Email -> unknown.
Now, connect the Filters to the action module: Send a chat message. You don’t have the email address to that person so the message will encourage him or her to provide you with that information:
“Hi there. Thank you for contacting us. None of our Customer Support Representatives are available right now. Please, provide your email address to stay in touch. Thanks!”