user-defined special-use folders

[Fabian Schmidt]

I plan to define SPECIAL-USE mailboxes and think about defining per user 
special-use folders for those who don't use the default folder names. Is 
this possible in dovecot?

What I try:
$ doveadm exec imap
* PREAUTH [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE 
IDLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS THREAD=ORDEREDSUBJECT 
MULTIAPPEND URL-PARTIAL CATENATE UNSELECT CHILDREN NAMESPACE UIDPLUS 
LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN 
CONTEXT=SEARCH LIST-STATUS BINARY MOVE SEARCH=FUZZY METADATA SPECIAL-USE] 
Logged in as fschmidt
a1 SETMETADATA "sent-mail" (/private/specialuse "\\Sent")
a1 NO [CANNOT] The /private/specialuse attribute cannot be changed (0.008 
+ 0.000 + 0.008 secs).

using dovecot 2.2.29.1, following the example in RFC 6154, sect. 5.4

(How is MAIL_ATTRIBUTE_INTERNAL_RANK_AUTHORITY defined or set?)

Fabian.