[Dovecot] IMAP COMPRESS not announced while using imap_zlib plugin

21 May 2011

      I'm trying to enable the IMAP COMPRESS plugin listed here:
http://wiki2.dovecot.org/Plugins/Compress
I have added zlib globally and imap_zlib to the imap protocol.
This is the output from doveconf -n with regards to mail_plugins:
--cut--
mail_plugins = zlib
protocol imap {
mail_plugins = zlib imap_zlib
}
--cut
But it seem like the feature is not announced when connecting to the
IMAP server:

OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE
IDLE STARTTLS LOGINDISABLED AUTH=DIGEST-MD5 AUTH=CRAM-MD5] Dovecot ready.

I would expect something like COMPRESS=DEFLATE.
I haven't enabled any compression for the Maildir files, zlib_save_level
and zlib_save is not set. Does IMAP COMPRESS only work if the mailbox is
compressed?
Best regards
Henrik Larsson