I have upgraded to Mavericks and have the latest version of SpamSieve.
There are a lot of mail that is being sent to the junk folder that is not junk.
When I get them and when I find one that is not junk I go to messages and train it as good.
The next time they come, again they are in the junk folder.
I also notice that the messages do not have a button for “Not Junk”