Messages are highlighted different colors according to how long they've not received a reply.

A message will turn green if it is a brand new unread message, then turn yellow after 3 minutes, and will then turn red if the message has gone over 5 minutes without a reply.

In order to mark a message as "read" - this will turn the message back to white - simply open up the message and either respond back, or click in the text area before closing the chat window.

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