Weird trackback spam

I’ve been getting a steady stream of trackback spam for several days now. They all come, supposedly, from IPs starting with 212.24.48.xxx, where the xxx changes with each post (all of which go back to some Russian ISP). They each come from “leriWinnerxx” where again xx changes with each post. It seems like this is just steadily cycling through every post on my blog and then going back and starting over again.

They are being caught easily by Trackback Validator and not appearing on the blog, though it does mean I get an e-mail on each one (anywhere from 5-10 per hour) asking me to moderate the comment. The comments don’t show up in the moderation queue, which means having to eliminate them one by from the link on the e-mail (which in itself seems odd). As best I can tell, they are simply some sort of google referral spam – probably to raise page rank: [HI! I’ve have similar topic at my blog! Please check it.. Thanks.] followed by a google search url.

My question, I guess, given that they’re not showing up in my moderation queue, and given that Trackback Validator is catching them – do I need to go through the trouble of deleting each one or can I just ignore them? If I ignore them are they busy filling up some disc space somewhere on my site? If so, is there a way to just go in and mass delete them once a day or so by editing some file?