[Dovecot] Dovecot-antispam does not work

[Jehan Pagès]

Hi,

I have installed dovecot-antispam and configured it this way (as in the doc)
with the dspam exe:


protocol imap {
  mail_plugins = antispam
  mail_plugin_dir = /usr/lib64/dovecot/imap
}


plugin {
# For dovecot-antispam:
        antispam_signature = X-DSPAM-Signature
        antispam_trash = trash;Trash;Deleted Items
        antispam_spam = SPAM;Junk
        #antispam_unsure = unsure

        antispam_dspam_binary = /usr/bin/dspam
        antispam_dspam_args = --deliver=;--user;%u

        antispam_mail_tmpdir = /tmp
}

But it does not work and really I cannot figure it out for two days, because
I can find no log wherever, where it writes it does (or try to do)
something, nor in the dovecot logs, nor in the dspam logs. But I know
something is happening because when I try to move a spam from my inbox to
the Junk folder, it fails with an error telling it could not move the email.
At the opposite, when I deactivate the antispam plugin, I can move normally
the emails.
So what could I do to fix my issue or at least diagnose it (where would I
find logs of what is happening?)?
Thanks.

Jehan