I can get rid of it if I reindex the right file, but EN World crashed on me last night when I was trying to. I decided to go to sleep instead. If Morrus or Eric knows which doohickey to frob, they'll do it -- otherwise, I don't think it's doing any harm.
Sadly spam is a hazard on the boards and in e-mail. If the problem becomes more common, maybe a kind word from Morrus or Piratecat might help. Or we could just assign offending posters to scrape barnacles off of Piratecat's ship.