as documented in bug 242378, the spambutt has a problem with expiring the bayes database. somehow a lot of atime entries get set far into the future, and the butt doesn't recognize this properl - and sits on its butt, chugging along and retrying the wrong things over and over again.
after finding a tool called db-to-text2.pl which can fix the entries and playing around with it i've decided to use the big hammer on bayesstore.pm: wherever atime is written to the db, we do a sanity check.
this patch addes these crude measures, and will hopefully keep my bayes dbs in fair shape. YMMV.