How to handle special use folders in Sieve?

[Bron Gondwana]

On Tue, 13 Sep 2016, at 17:25, OBATA Akio via Info-cyrus wrote:
> Hi,
> 
> Since 3.0.0-beta2 release note's "Major changes since the 2.5.x series":
> 
> * Sieve now supports special use folders. See Cyrus Sieve
> 
>   http://cyrusimap.org/imap/admin/sieve.html#cyrus-sieve-specialuse
> 
> But I cannot find how to do it in sieve script.
> 
> For example, how to rewrite following script with such feature?
> 
>    if header :is "X-Spam-Flag" "YES" {
>      fileinto "INBOX.Junk"
>    }

if header :is "X-Spam-Flag" "YES" {
   fileinto "\\Junk"
}

Bron.

-- 
  Bron Gondwana
  brong at fastmail.fm