[For 1.6] [release] [updated for 1.6] Stopforumspam.com plugin for MyBB - Stop the Spam!

[Tim B.]

I'm not sure, I doubt you blocked them unless you're on a shared/free host that has some issue with them or something, in which case you would have to contact your host. Otherwise it's possible that another site on your shared server which uses your IP was banned for abusing their services or something, you would have to ask at SFS.