Rspamd 的 EXIM 配置中存在未知 ACL 条件/修饰符

我正在尝试将 EXIM 配置为使用 Rspamd 作为垃圾邮件过滤器。我正在运行 Exim 4.87 版，并使用此处apt-get解释的方法从存储库安装 Rpsam 。然后我将Rspamd 文档中的建议配置添加到我的配置文件中：

begin acl

# configure Rspamd
# Please note the variant parameter
spamd_address = 127.0.0.1 11333 variant=rspamd   # error occurs here

acl_smtp_data = acl_check_spam

acl_check_spam:
  # do not scan messages submitted from our own hosts
  accept hosts = +relay_from_hosts

  # do not scan messages from submission port
  accept condition = ${if eq{$interface_port}{587}}

  # skip scanning for authenticated users
  accept authenticated = *

  # add spam-score and spam-report header when told by rspamd
  warn  spam       = nobody:true
        condition  = ${if eq{$spam_action}{add header}}
        add_header = X-Spam-Score: $spam_score ($spam_bar)
        add_header = X-Spam-Report: $spam_report

  # use greylisting available in rspamd v1.3+
  defer message    = Please try again later
        condition  = ${if eq{$spam_action}{soft reject}}

  deny  message    = Message discarded as high-probability spam
        condition  = ${if eq{$spam_action}{reject}}

  accept

当我尝试重新启动 Exim 时，我收到以下错误消息：

error in ACL: unknown ACL condition/modifier in "spamd_address = 127.0.0.1 11333 variant=rspamd"

这是指我上面发布的配置代码的第 4 行：spamd_address = 127.0.0.1 11333 variant=rspamd. 我在官方 Exim 文档中找到了完全相同的行。所以它应该工作。之前有人在配置 Exim 以使用 Rspamd 时遇到过这个问题吗？

我正在使用 Ubuntu：

$ uname -a
Linux calais 4.4.0-36-generic #55-Ubuntu SMP Thu Aug 11 18:01:55 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux