As In Search of L33t says, comment spam can be a large scale annoyance. In L33t’s words:
I am promising myself I am going to start blogging more. The main problem is that I am so tired of blog spam. Even with the comments turned off I am still getting blog spam. It depresses me a little to see so many blog comments that have absolutely nothing to do with my topics.
I have similar blog spam levels:
mikal@daedalus:~/blog-comments$ du -sh
mikal@daedalus:~/blog-comments$ find . -type f -name "*.no" | wc -l
mikal@daedalus:~/blog-comments$ find . -type f -name "*.blocked" | wc -l
mikal@daedalus:~/blog-comments$ find . -type f -name "*.yes" | wc -l
Yes, that really is 79 meg of blog comments (admittedly including the metadata for recent comments). The most interesting bit is that blocked line. That’s the number of posts which have been automatically blocked since I started automatically blocking some posters. It’s been really effective, I get around one or two comment spams in my email for moderation a day now. The super secret algorithm? I block these IP addresses:
I recommend others give it a try, as it’s eliminated basically all of my comment spam. That’s right, it appears to me that almost all comment spam comes from these few IPs.