Best Practice for Setting Up and Adjusting Spam Confidence Level Thresholds

Best Practice for Setting Up and Adjusting Spam Confidence Level Thresholds

We recommend that you set up and adjust the spam confidence level (SCL) thresholds as follows:

1. Enable the SCL delete, reject, and quarantine thresholds on the content filter configuration on each Edge Transport server. We recommend that you start with the default values for these SCL thresholds. The default values were set by the Exchange Server team according to real-world data from the Microsoft IT messaging department and from Exchange Server 2007 early adopter feedback. The default values are optimized for large, global enterprise deployments.
2. Enable and configure per-recipient SCL thresholds. At a minimum, you should enable and set the SCL Junk E-mail folder threshold on each user's mailbox. You can also configure the SCL delete, reject, and quarantine thresholds on a per-recipient configuration. Also, you can set exceptions on each user's mailbox so that messages to that mailbox bypass all anti-spam scanning on the Edge Transport server.
3. Monitor spam reports and logs closely for the first week after you enable the SCL thresholds. If the data indicates that you must make immediate adjustments, reconfigure the SCL thresholds. Otherwise, collect data and analyze the spam reporting to determine whether adjustments are required.