I get a TON of cyrillic spam for some reason. I've heard of other spam blockers that permit one to set a language filter so that emails in a foreign language or that are in a different character set are blocked. I'd REALLY like to see such a feature added to NIS.
I get two tons, everyday, probably 98% of all my spam has Cyrillic characters. Implementing this options would be a huge improvement in the anti-spam feature