Email filter or rules integration

I'm getting dumb spammers trying to post comments with their spam. Their email box is full so I get the verification email bouncing back to me (I did say they were dumb!). I've added a rule to delete their posts (based on their email address) but it still triggers the verification email being sent. It would be useful to have a filter in email verification or for comment verify to invoke rules before sending the verification email.

Note I've tried triggering a rule to delete the post before save but that doesn't seem to trigger. I have to trigger on save to get it to delete which is after verify comments has sent the email. I currently trigger the rule on both before save and after save but I think only after save is actually triggering.