[Dovecot] search and UTF-8 normalization forms (NFD)

[Lutz Preßler]

Hello,

on a system with dovecot 2.2 I've got a mailbox containing multiple mails
from a person called Krüger, but From: header encoded differently.
Some are encoded in UTF-8 normalization form decomposed (as used by Mac OSX),
that is u and umlaut accent as sperate combined codepoints
instead of one ü:

  From: =?utf-8?Q?replaced_Kru=CC=88ger?= <krueger at some.domain>

Searching within roundcube webmail for "krüger" as sender
missis this mails.

Roundcube sends (dovecot rawlog):
A0003 UID THREAD REFS UTF-8 ALL HEADER FROM {7+}krüger

Is this supposed to work? Haven't done any more debugging
(other search variants) or read RFCs. As a user I would expect
Unicode equivalence rules be applied (see 
http://en.wikipedia.org/wiki/Unicode_equivalence)

Regards,
  Lutz