Hello, I'm building segments in Acumbamail and have a question about the Quality filter.

1. How is a subscriber's quality ranking calculated? Does it use opens, clicks, or both?
2. What are the possible levels, and what does each one mean?
3. Are automatic opens (such as Apple Mail Privacy Protection) and bot or security-scanner clicks excluded from it?

I want to use it to separate engaged subscribers from inactive ones, so I need to know how reliable it is. Thanks!