imapc and THREAD

[Olaf Schuemann (privat)]

Hello,

at the moment i get a "strange" behavior on imapc (imap proxy mode) and 
thread/sorts in version 2.2.25 (I also tried 2.2.23 with the same result)

In imapc mode an IMAP request like
. THREAD ORDEREDSUBJECT UTF-8 SINCE 5-MAR-2000

gets as response
* THREAD (1 
(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(22)(21)(23)(24)(25))

the same request on the origin server gets the correct response
* THREAD 
(18)(19)(25)(24)(20)((4)(7)(12)(23))(1)(2)(3)(5)(6)(8)(9)(10)(13)(14)(15)(16)(17)(11)(22)(21)

Is there a config param to "activate" thread? Missing something else?