So I've been running version 16 a couple weeks or so now, and Greylisting has been enabled (without the ability for domains to disable) but the reports are showing zero Greylisting activity at all.
Is this a bug or what? It doesn't seem too involved to enable, Settings -> AntiSpam -> Grelisting Options are set to:
Block Period (Minutes): 1
Pass Period (Minutes): 360
Record Expiration (Days): 90
Enable Greylisting is on, Users can override greylisting is off.
Whether looking at the Greylisting report as system admin or domain admin there is nothing there.