I think this might be a bug which has been around a while (like a high number of months). And we have a few anti-spam addons which might be getting in the way. But we occasionally (like maybe once a week or more) get a user registration moderation queue item because of stopforumspam which reports the number of instances of the email or IP or username from SFS as 255. Which is a significant number in the computing world. And example from just now. I checked the email address on SFS and there were no hits. Which makes me think that maybe there is a bug here?