What happened to ADVO? Well they got taken over by Valassis last year.
You can still go to www.advo.com/consumersupport.html to opt out of ADVO flyers. It will take 5-6 weeks to become effective.
You can also call Valassis’ Consumer Assistance line toll free at 888-241-6760 (8:30am-5:00pm EST) or print this form and mail it in.