The earlier entries in this web log have been spammed with hundreds of trackbacks to sites that are, at least, annoying. The subset of the blojsom web-log server that Apple supplies with Mac OS X Server has no built-in way to remove offending comments or trackbacks. 
 
I'm searching for a solution, and I'll apply it as soon as I can. Sorry. 
 
Update: I've learned how to suppress trackbacks entirely, which does the trick. Apple's blojsom doesn't allow moderation of comments or trackbacks.