HELP - Mail App sent many of my emails to my Junk box

All of the sudden I see like 364 emails inside my Junk mailbox. These emails were all old emails that have always been in my Inbox and many of them I had even answered to and were from friends that appear as my contacts.

This is ridiculous, please someone tell me where can I find the solution for this.
Thanks

I am also finding that emails are ending up in my Junk folder, when they are not. That would not bother me so much, but they are not marked Junk, so there is no way to re-code them as Not Junk, so the problem does not go away. Anybody else seen this and have an answer?