unread

Mark a direct message sent to you unread again, so list with unread shows it until you next read it. Your read marks are yours alone and live on this device; nobody else's change. The messages you sent are always read, so unread of one refuses; so does a message addressed to someone else, and one removed after 7 days.

For example, an agent that read a request it cannot act on yet marks it unread, so it comes back up the next time the agent lists what is unread.