That is much better than the two lines.... however....
It seems to me the date would still be desireable although I suspect the order remains in inverse chronological order. You could change it to say:
Unread Public Messages (Inverse Chronological Order) Kept Public Messages (Inverse Chronological Order)
But, also, it appears to me that there is plenty of room on the SAME LINE for the addition of the board name AS WELL AS the date. That would seem to me to be the best of all worlds.