Haha trust me I know how fast they can move... At least give it a day or two's trial I say.
You need some sort of a system which moderators can ban people for "x" amount of days from the shoutbox if they're spamming. It's in the moderators discretion to choose how long. Until then the spammer can only contact the moderator and the decision will lie in the moderators hands.
There is perfectly rational ways around the spammers... You guys have to trust me when I say the shoutbox works well...
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