dovecot - Aug 2010 - pigeonhole and utf-8 error

Hi,
now, I'm working with the last version of dovecot and pigeonhole sieve,
and when apply a sieve filter on a new message, and it try to move this 
mail to a folder with special character
like accent give me the error 'mailbox name not utf-8: ...'

 >Aug 17 09:22:40 imap1 dovecot: lmtp(19629,miel): Error: 
kea6K484akytTAAAJBW4rA: sieve: msgid
><1099311971.505.1282029699154.JavaMail.open-xchange at o.uib.es>:
failed
to store into mailbox 'atenci?': >mailbox name not utf-8: atenci?

dovecot it's working without problem on this folder.
I suppose it's a misconfiguration, but I don't find where...

Xavier

On Tue, 2010-08-17 at 09:35 +0200, Xavier Pons wrote:
>  >Aug 17 09:22:40 imap1 dovecot: lmtp(19629,miel): Error: 
> kea6K484akytTAAAJBW4rA: sieve: msgid> 
><1099311971.505.1282029699154.JavaMail.open-xchange at o.uib.es>:
failed
> to store into mailbox 'atenci?': >mailbox name not utf-8:
atenci?
> 
> dovecot it's working without problem on this folder.
> I suppose it's a misconfiguration, but I don't find where...
I guess you wrote the script with ISO-8859-x charset or something
instead of UTF-8.