There is a bug going on around the server, where non-donators chat always ends in question marks, when it's not intentionally put there. Here's an example from Spleef
Oh ok, Im was in this time, but i don't set the proof. But is this happen in my too. (Im the Herobrine Rank)
I think it happened after the server restarted, hopefully it gets fixed soon. Otherwise you don't know whether people are asking a question or making a statement.