Chat datadase How to now email id of offline chat visitors

I am using chat plugin in but dont know from where i can get offline chat database means when i login in site then i get previous chats scrolled in chat panel on my site but i want to see all chats with their email id bcoz every time when any visitor want to chat on site then they have to submit their email id so pls tell me how can i access all offline chat details with email id..

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