Thanks. I had forgotten about autofiltering, and playing with file options I found it, and disabled it. 

I have a folder system with a lot of items developed over the years. I also have filtering rules set up, some before reading some after.  I find that one correspondent is being automatically sent to one of my folders without the authority of any rule in my rule set.  Any clues here?

If the redirection occurs when the messages arrive its either an Autofilter or a new mail filtering rule.

• To check for an Autofilter:  With the Folder list open or while in Preview mode go to the Folder pull-down menu and select Manage Autofilters to see a list of any that exist.
  
• Rule out the possibility that one of your new mail filter rules is acting on these messages by temporarily disabling your new mail filtering rules then seeing if it still gets redirected.  An easy way to disable the new mail filter rules is to add an "Always exit" rule as the first rule.

You probably know this but for anyone who doesn't, you can test new mail filtering rules on a specific message by copying or moving that message to the new mail folder, marking it as unread, and then closing/reopening the new mail folder.