sympl-mail: config/antispam doesn't work as expected

What is expected to happen:

With the antispam file at /srv/example.com/config/antispam and empty, spam mail identified as spam should be rejected.
With the antispam file at /srv/example.com/config/antispam and containing tag, spam mail should:

have the X-Spam-Status: spam header set, and the mail accepted.
be delivered to the Spam mail folder of the user.

What actually happens is that 1 works as expected, but 2 rejects the mail as spam regardless of the tag setting, unless the config/antispam file is world-readable, which it likely shouldn't be.

In no instance (apparently inherited from Symbiosis) does the mail actually get placed in the users Spam folder, although it would be possible to create a sieve filter to do this, or for Dovecot to handle it, the mail is placed in the normal mail folder.

A quick fix would be to change /etc/exim4/sympl.d/10-acl/50-acl-check-rcpt/80-enable-antispam-check to:

${if match{${extract{smode}{${stat:VHOST_DIR/${domain}/VHOST_CONFIG_DIR/antispam}}}}{\Nr\N}{\

A fix for tagging spam properly would be to enable the subject rewrites by default, by adding the following to /etc/exim4/system_filter:

if $h_X-Spam-Status: contains "spam"
then
   headers add "Original-Subject: $h_subject"
   headers remove "Subject"
   headers add "Subject: *** SPAM *** $h_original-subject"
endif

Note this also affects config/antivirus, which has a similar (undocumented) tagging function for virus infected emails in /etc/exim4/sympl.d/10-acl/50-acl-check-rcpt/85-enable-antivirus-check.