CLOSED versus OPEN mode in Domain Options
When a Norman spam filtering account is initially setup it will by default be in OPEN mode. This means that Norman will process all messages regardless of who they are addressed to. This setting is desirable for large accounts that want to make sure they do not miss any addresses. They may want to later switch to CLOSED mode once they are certain of all their addresses. The downside to the OPEN mode is that your spam quarantine can become filled with several thousand invalid addresses.
Setting your domain to CLOSED mode will only process mail for the addresses entered in the Users section of the web interface. All other addresses not specifically entered into the web interface will be rejected. Having your domain set to CLOSED has many advantages. The most obvious advantage is that the domain admins will not have wade through large amounts of spam destined for invalid users. The downside to the CLOSED mode setting is that domain admins will have to be certain they have all the user address, alias accounts, email groups or email lists entered into the web interface under the Users button. If an address is not listed in the Users section all emails destined for that user will be rejected. Of course it would probably not take long for the missed users to realize they are not receiving email and promptly notify you.