I’m having problems with the SCL (Spam Confidence Level) on MICROSOFT Exchange 2007/SBS2008, it started with clients getting ‘failure notice’ or ‘Mail delivery failed: returning message to sender’ emails with the error: 550 5.7.1 Message rejected as spam by Content Filtering. So I examined the Agent Log file in the Transport Roles\Logs folder and found the error SclAtOrAboveRejectThreshold, 7 which I think means reject messages that have an SCL rating greater than or equal to 7. I reviewed more Agent Logs and traced other occurrences of this happening to other clients, how can I fixed this but also allow the SCL to do its job of rejecting spam?

Also what is the appropriate size for a mailbox on Exchange 2007, I think default the quota was around 5GB but I have removed the quota for a couple of users & wasn’t sure how to approach this. Does the Server hardware or amount of disk space make a difference, should I get the user to do some housekeeping in Outlook?

Thanks for your time