spam in comments

I don’t have comments enabled on this main blog (mainly because I never got round to enabling them), but I do on my skate blog, and recently found some anonymous links to some directory site buried among the comments, which really annoys me. I’ve been lucky so far, i’ve heard that this type of spam is rife – I think maybe my obscure blog software has kept me out of the loop to a certain extent. Anyway, the spam was deleted, and if it reappears I may just have to change the comments to "approval only" – i’d been thinking of doing this anyway because I don’t get notified when comments get added and sometimes I miss them.