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I take it you didn't read the thread? Yep we've considered it, yep its flawed - It will only respond once. The next time the user chats when you're disconnected they won't get the message... ......

This feature request has been open too long without action. The suggest to use the "Auto Respond to Message" extension goes some way to helping with this; unfortunately the extension only responds to the the user once, instead of each time a user tries to communicate via chat with no host connected.

If implementing this feature request is too difficult, please fix the extension to respond each time (and include an option to toggle email notifications on/off)