message filter on old and new mail

I have a mail filter rule setup to move incoming message attachments to a local folder. It seems to only work when I am receiving a unread email message. If there is an incoming message that for instance i read it on webmail than I notice the message filter does not run! Is there a workaround for this? I want any incoming mail old and new to be filtered according my message filter rules. I am using imap protocol.