Enables or disables the ability to enable SpamAssassin configuration on a per-domain basis. With this enabled, you may disable spam filtering for some domains while enabling it for others. You may wish to disable this, if you will enforce spam filtering for all users, or if you are using an alternate spam preventative system on a system-wide basis. Note that server-wide configuration is not handled by Virtualmin. You will need to enable it using the SpamAssassin Webmin module, if you prefer server-wide spam filtering.