[Dovecot] expire plugin - setgid failed

[e-frog]

Hello all,

I'm trying to get the expire plugin working, but still having issues 
even with 1.1RC5.

If I run the expire tool I get the following error:
server:~# dovecot --exec-mail ext /usr/local/libexec/dovecot/expire-tool
Fatal: setgid(100) failed with euid=2005, gid=0, egid=0: Operation not 
permitted

Same thing with --test:
server:~# dovecot --exec-mail ext /usr/local/libexec/dovecot/expire-tool 
--test
Fatal: setgid(100) failed with euid=2005, gid=0, egid=0: Operation not 
permitted

gid 100 = users, uid 2005 = helmut

The user mail box has the following permissions:

root at LINKSTATION:/home/helmut# ll -n
drwx------   22 2005     100          4.0k May 17 13:14 mail

Any help is appreciated.

Thanks,

Helmut


server:~# dovecot -n
# 1.1.rc5: /etc/dovecot.conf
log_path: /var/log/mail/dovecot.log
info_log_path: /var/log/mail/dovecot.log
ssl_disable: yes
disable_plaintext_auth: no
login_dir: /var/run/dovecot/login
login_executable: /usr/local/libexec/dovecot/imap-login
login_process_size: 16
max_mail_processes: 16
mail_location: maildir:%h/mail
umask: 7
mail_plugins: quota imap_quota mail_log expire
namespace:
  type: public
  separator: /
  prefix: Public/
  location: 
maildir:/home/public/mail:CONTROL=%h/mail/control/public:INDEX=%h/mail/index/public
  list: yes
  subscriptions: yes
namespace:
  type: private
  separator: /
  inbox: yes
  list: yes
  subscriptions: yes
auth default:
  verbose: yes
  passdb:
    driver: pam
  userdb:
    driver: passwd
  socket:
    type: listen
    client:
      path: /var/run/dovecot/auth-client
      mode: 432
      user: dovecot
      group: mail
    master:
      path: /var/run/dovecot/auth-master
      mode: 384
plugin:
  quota: maildir
  quota_rule: *:storage=1GB
  quota_rule2: Trash:storage=10%%
  expire: Trash 1
  expire_dict: proxy::expire
dict:
  expire: db:/var/lib/dovecot/expire.db