Q: Once you move a junk email to the Junk folder, does Apple know it's junk mail?  How long does it take Apple to realize its junk?  If I delete it right away will Apple had had a chance to log it as junk?

If you assign it to junk via the Junk button at the top it will be reported to Apple at spam@icloud.com. I also notify Apple and the Govt by forwarding the email with full headers displayed as an attachment to spam@me.com amd spam@uce.gov.

More info here: iCloud: Why was I spammed?

OT

Message was edited by: Old Toad

I assumed you were referring to on a Mac.  I don't know.  I take the time to alert Apple to the problem as I posted in my first post. I've created a macro that will do that automatically.  That gives Apple a heads up so they can refine their spam filters at the server.