Scenario: Spam Filter Debian Sarge 3.1/Postfix2.1.5/Mailscanner(Mail Relay Gateway) ----> Exchange 2000 Server My Exchange 2000 server does not have the ability to know whether to reject or accept mails for users that no longer exists, therefore creating a ton of undeliverable messages in its queue. I came accross the Postfix check_recipient_access feature, which uses a file to store user email information that Postfix can use to decide whether to accept of reject emails. However, I don't know how to set this up. I need the spam filter to have to ability to reject mails for certain users that no longer exists. My main goal is to cut down on the amount of undeliverable mails in my Exchange 2000 queue. Also, is there a way to create a local user account on the spam filter that can be a catchall mailbox? I also would need pop3 access into this mail box to read emails if my Exchange box goes down. I need to create a failsafe if the Exchange box should puke, which I think it will.... Any help would be greatly appreciated. Thanks. UPDATE: I've successfully set up a Postfix access file that stores email addresses to reject. Therefore, I only need help to create the catchall email account. Thanks.