I found the thunderbird support forum by clicking on "support forum" at the top of the page (home>support forum>firefox). This option doesn't appear in the list at https://support.mozilla.org/en-US/questions/new.

This is strange -- i posted this in the firefox forum but it's appearing here.

Anyway, the problem is that I've been marking emails as junk but they thunderbird keeps not learning that they are junk. I've marked them repeatedly. Don't know if there's a problem because the account server 1is imap yahoo.

Also, when I try to mark a message as "not junk" by using "J" I don't see any mark or response to show that it's been marked.