The merit system has reduced a lot of spam, those who used to rank up by posting spam now they have no chance. So if they want to stay in this forum now and rank up, they have no choice but to post good. Without signature, forum traffic will drive in the other direction., because signature makes members more interested in discussing in the forum and prefers to find and share new things. And if you think a post is spam, you can direct report it to the moderator, so the moderator can take appropriate action on that post.

However, it seems to me that the newbie account spams several times more than the spam from the signature account, whose job is to shilling about a project and bumping ann. So now how to control those spammer accounts?