OK. I have been reading the thread on this bug:
Bug 9532 – IMAP/Outlook move to junk doesn't train anti-spam
I'm not sure how to know if Spam training is occurring. In my example I'm using thunderbird with IMAP. I have a junk folder and when i tag an email as junk it moves it there. How do I know if it is also doing the extra step to train the spam account? Does this work on all clients running IMAP ?