How do I find the reason for a message SCL value?

We are having issues with legitimate emails going to users Junk E-Mail folder. When looking at the message headers I see X-MS-Exchange-Organization-SCL: 5

With default settings SCL values of 4-6 will go to Junk. I don't necessarily want to change this, but I do want to understand why this email, that clearly isn't spam, is being marked with an SCL of 5.

Is there some logging that will show me why? Or something else in the message headers that might explain?

Thanks