add delete all box when your spam folder is full 1000 instead of doing it 1by1 you could block the well known ones better than you do????
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C. R. commented
when you hover over the spam folder, a 'trash can' ion appears to the right. click that and it deletes all of them, or at least it's supposed to, I've never had 1,000 spam emails to delete. yahoo also automatically empties that folder after 7 days too.