There are four Services that you should use at a minimum when setting up an Inbound Mail Filter Policy.

1. Block - this will stop the email from being delivered to the user.

2. Quarantine - this will send the email to the quarantine.  It does not block emails.  If a filter is only connected to this service, it will be quarantined, but it will still be delivered to the user.  You should typically connect a filter to both Block and Quarantine.

3. No Quarantine - this will prevent the email from being quarantined.  You should create this service to make sure that emails (such as ones that contain a virus) never get in your quarantine.  Make sure to attach those filters to both Block and No Quarantine.  A no quarantine service takes precedence over a quarantine service!  You create the no quarantine service by placing another quarantine service, expanding it, and setting it to "Force service off".

4. Quarantine Control - this will control what a user can and cannot release.  This is for the in-between cases.  For example, you may have something that you want to go to quarantine, but you only want the admin to be able to release it.  Using Quarantine Control you can prevent a quarantined email from showing up in the user's digest (disable digest) and also prevent the user from releasing the message (disable message release).