Maybe you can tell spam filter postfix to HOLD all mails to your domains and then just remove hold and postsuper -H ALL ?
like this: http://wiki.zimbra.com/index.php?title=Irfan-Notes#Holding_the_Postfix_Queue_at_time_of_server_migration.2Fmaintenance and man 5 access and look for HOLD ? -- Eero
