i find a useful article on spippolazione http://spippolazione.net
“Thread View” does not work
ERROR: Bad or malformed request.
Query: THREAD ORDEREDSUBJECT ISO-8859-1 ALL
Server responded: Error in IMAP command UID: ORDEREDSUBJECT threading is currently not supported.
You need to log into Squirrelmail then click on “Options” then “DisplayPreferences” and make sure that “Enable Thread Sort by References Header” is set to “yes”.