dovecot - Nov 2013 - Getting debug output from antispam plugin with dspam

Hello.

I'm trying to get some output from antispam plugin when it invokes dspam
binary for retraining.
Currently I see no messages related to dspam execution.

Dovecot IMAP server works as 'vmail' user:
# ps aux|grep 'dovecot/imap'
vmail     3062  0.7  0.0  29824  3008 ?        S    16:22   0:00
dovecot/imap

User 'vmail' is listed as trusted in /etc/dspam/dspam.conf
# fgrep vmail /etc/dspam/dspam.conf
Trust vmail

Dovecot IMAP plugins and antispam configuration:
# doveconf -n | egrep -e '(^#|antispam|protocol imap)'
# 2.2.7: /etc/dovecot/dovecot.conf
# OS: Linux 3.7.10-1.16-default x86_64 openSUSE 12.3 (x86_64)
  antispam_allow_append_to_spam = YES
  antispam_backend = dspam
  antispam_dspam_args
--client;--user;%Lu;--deliver=spam,innocent;--source=error;--signature=%%s
  antispam_dspam_binary = /usr/sbin/dspam
  antispam_dspam_notspam = --class=innocent
  antispam_dspam_result_header = X-DSPAM-Result
  antispam_dspam_spam = --class=spam
  antispam_signature = X-DSPAM-Signature
  antispam_signature_missing = move
  antispam_spam = Spam
  antispam_trash = trash;Trash;Deleted;deleted;Deleted Items
protocol imap {
  mail_plugins = expire mail_log notify quota trash imap_quota antispam

Antispam plugin is successfully loaded:
# grep antispam_plugin /var/log/dovecot/dovecot.log
Nov 11 16:22:32 imap: Debug: Module loaded:
/usr/lib64/dovecot/modules/lib90_antispam_plugin.so

As i understand plugin would not work with message that do not contains
dspam signature, so
I sent GTUBE message to myself and when I move it to Spam folder I see only
Dovecot messages:
Nov 11 16:28:06 imap(zinovik at example.org): Info: copy from INBOX: box=Spam,
uid=3422, msgid=<20131111144014.731f035b871deb0e082bc22e at example.org>,
size=1130
Nov 11 16:28:06 imap(zinovik at example.org): Info: delete: box=INBOX,
uid=26792, msgid=<20131111144014.731f035b871deb0e082bc22e at example.org>,
size=1130
Nov 11 16:28:06 imap(zinovik at example.org): Info: expunge: box=INBOX,
uid=26792, msgid=<20131111144014.731f035b871deb0e082bc22e at example.org>,
size=1130

Dspam logs nothing, though debugging is turned on
# ps aux | egrep -e '^dspam'
dspam     2939  0.0  0.0 116408  2420 ?        S    15:38   0:00
/usr/sbin/dspam --daemon --debug
# egrep '^Debug ' /etc/dspam/dspam.conf
Debug *

Even if I set dspam binary to file that do not exist i do not get any
debugging messages (according to
code function i_debug("execution %s failed...") should be triggered).

Maybe there is some kind of verbose output knob for plugins in Dovecot?  I
turned on everything I found (also using mail_log for imap protocol):
# doveconf -n|egrep -e '(verbose|debug)'
auth_debug = yes
auth_verbose = yes
mail_debug = yes
verbose_ssl = yes


Is there anybody out there who use Dovecot 2.2.7 with antispam plugin?

Antispam plugin revision
5ebc6aae4d7c<http://hg.dovecot.org/dovecot-antispam-plugin/rev/5ebc6aae4d7c>