Don't understand the necessity of this service? How is this better than spam blocking which is already integrated into most email services?
Not all, meaning Exchange 2013 relay on a 2nd layer from being hit of spam, or companies are doing their own mailing server.
Hints why services like "barracuda" are still alive, my SpamFirewall works the same as "barracuda" with out having the actual system on hand and/or the expense of that system.
on DNS MX record you point to our "NocRoom SpamFirewall" then our system will relay back to you clean emails, Again this is only for companies running their own mailing server