[Dovecot] Sieve plugin: Filtering UTF-8 Emails

hi all,

i hope it´s okay for questions about the sieve plugin here... my problem is, that the filters do not seem to match utf8-content

for instance: the email:

Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Subject: =?utf-8?Q?Erinnerung:=20Bitte=20f=C3=BChren=20Sie=20die=20Kaufabwicklung=20durch?=

when i use the same subject (of course in utf-8) in my ".dovecot.sieve", the filter never matches ;-((

does anyone have an idea howto make the sample here matching by sieve ???

thank´s for any help! michael