Akismet is fine, but I decided to write a simple WordPress comments antispam for research resons. There are some proven methods to fight against spammy comments:
- honeypot field “nick”, it is hidden by CSS – only bots will fill it
- block comments with BB code [url=…]
- HTTPBL (DNSBL) from http://www.projecthoneypot.org – you need API key
- Block comment with common bad words
- Block direct POST requests (no referer)
- Swap regular comment textarea with honeypot field
You can try it and provide me some feedback or samples of unrecognized spam. I’m playing with more methods like language detection or bayesian filter and I can try to implement them in the future.