You run the Exchange 2007 BPA and see the following information (warning) items:
Junk Store threshold is currently configured to move messages to recipient’s Junk folder when they have a Spam Confidence Level (SCL) value of 8. This is the default value for the Junk Store threshold. However, the recommended value is 4. You can configure SCL thresholds by using the Set-OrganizationConfig cmdlet in the Exchange Management Shell.
Following the link on the BPA, which takes you here, tells us the correct setting for the SCL Junk Threshold is 4. Im good with Microsoft recommendations, more so if it stops errors. You can change this number depending upon your organization and your desire to block out spam. The lower the value, the more “spam” is blocked, including what Exchange thinks is spam and may be good mail. I have had issues with spam in the past, 4 sounds way better than 8.
This is done by the Exchange Management Shell. Open it up from the start menu, the navigate to the scripts folder by typing in the command:
cd “C:\Program Files\Microsoft\Exchange Server\Scripts” including quotes.
Simply type in:
set-organizationconfig -scljunkthreshold 4
If you get no error, the issue is solved. If too much good mail is being trapped in spam folders, change this to 5 or 6. If you want more mail captured- spam is getting through- change this to 3. Personally I would not go higher than 3, and if you go that high make sure you enable a transport rule to give mail sent from your users a rating that will allow it through.