[X4U] Weird Mail problem..infinity loop of sorted /deleted mail

[Michael Elliott]

Just starting the last 2 days or so, whenever I delete mail from one of 
my mailboxes (i.e. the "[X4U]" mail is sorted to my "OSX List" box), 
the mail gets added to the appropriate Trash box...but as soon as I 
click the OSX List mailbox, the mails are back again, sometimes 
duplicated, and if I re-delete them, they're just re-added to the 
trash.  This occurs even if I erase deleted mail.

So...trash is emptied.  6 emails are in the OSX List mailbox.  I read 
them, then select all, then hit the Delete key.  I then control-click 
the Mailboxes pane, and select Erase Deleted Messages.  I then 
re-select the OSX List mailbox...to find the same 6 emails.  When I 
repeat delete-->erase deleted mail procedure and then re-check the 
trash folder, I now have 12 emails in it...and the same 6 emails in my 
mailbox.  I can repeat it until there are hundreds of the same mail 
message present in the trash.

I've tried deleting the entire Mail folder in ~/Library/  as well as 
the Mail .plist files in /preferences, but don't seem to be able to fix 
this one.

Any ideas?

Michael