I noticed that a very large proportion of the comment spam I get is all on one blog entry, number 20. So a quick
update mt_entry set entry_allow_comments = 0 where entry_created_on < now() - interval '180 days' and entry_author_id = 2;
and now nobody can comment on entries that are older than 180 days. I'm just wondering if I should do the same with the other blog authors.