Contact Form 7 supports spam-filtering with {bbackup_94402fb9ba80f392e0976ece85f92b2b876bfcaed8d83250cc06083f7139c7d9}1$s. Intelligent {bbackup_94402fb9ba80f392e0976ece85f92b2b876bfcaed8d83250cc06083f7139c7d9}2$s blocks annoying spambots. Plus, using {bbackup_94402fb9ba80f392e0976ece85f92b2b876bfcaed8d83250cc06083f7139c7d9}3$s, you can block messages containing specified keywords or those sent from specified IP addresses.