When you create the filters in the "Smart List" tab, navigate to the "Schedule" tab. In the "Smart List Status" section, it will tell you how man leads are blocked from mailings. Click through to see details.
Thats what I thought, however, the list that I uploaded contains 3456 people. I have two filters on, when I go to the schedule tab where you advised, it says 0 leads are blocked from mailings, however its only set to affect 3192 leads...
I figured it out. 🙂 There were "safe guards" put into place before I started. a list that was set up basically the same as who is blocked from mailings by Marketo. All good. Thanks Keith!