Spam Blocking at Coinet

Coinet actively rejects spam email.  We receive over 7,000,000 emails
each week and, unfortunately, well over 95% of it is spam.  We
immediately reject over two-thirds of that email (the criteria are
listed below).

Unfortunately some mail server administrators inadvertantly disguise
their point of origin or legitimate email senders find themselves
using a spam email server for their normal email.

If that is the case and aunt Gertrude sends you an email and we block
it we always send a bounce message detailing the reason for the
rejection.  Aunt Gertrude should have received the bounce message.

We must see the bounce message before we can help track down the
reason for the delivery failure.  Without the bounce message we no
clues about why the delivery failed.

At ingress Coinet blocks mail from:

   1) Mail servers that hide their identity.
         Federal Law probits emails senders from disguising their
            point of origin.
         RFC 1912 Section 2.1 requires working reverse DNS to
            determine a true point of origin.
         We block all mail for which reverse DNS does not work.
            Two lookups must work and match to have working reverse DNS:
               [Sender IP]    --lookup-->  [URL from DNS]
               [URL from DNS] --lookup-->  [IP from DNS]
               [Sender IP] and [IP from DNS] must be exactly the same.
            Software automatically identifies the offending mail servers.
         We alway send this reject message to the sender: 
            Attention!  Reverse DNS on the originating mail server does
            not work.  It is not in compliance with RFC 1912 section 2.1
            The sysadmin of the originating mail server must fix this problem.
   2) Mail servers that have sent double bounce spam to us.
         A double bounce spam email is one which:
            Is addressed to a fictious email address at Coinet.
            Has a fictious return email address.
            Has a very high spam score.
            Software automatically adds offending mail servers to this list.
         We always send this reject message to the sender of any further email:         
            Your email has gone to spamheaven.  Why?
   3) Mail servers that have sent a LOT of spam to us.
         These mail server have send a large volume of high spam score
            email to us.
         These mail servers have not send legitimate email to us.
         These mail servers have a domainname like "" or
            "" or ""
         These mail servers are added to this list by hand (ugh!).
         We always send this reject message to the sender of any further email: 
            Your email went to spamheaven.  Why?
   4) Hacked computers (virus infected) on cable or DSL connections.
         Unbeknownst to their clueless owners a large number of computers
            on cable and DSL connections to the Internet have become virus
            infected and are now significant sources of spam.
         These computers are identified by the domainname the cable or DSL
            provided has created for the IP number assigned to the connection.
            These domainnames typically contain the IP along with words such
            as 'user', 'adsl', 'cable' or 'client'.  Legitimate mail server
            domainnames are very different, they do not contain the IP number
            and are more like or
         We assign a score to the domainname of each mail server that attempts
            to send mail to us and reject mail from servers with high scores.
         We always send this reject message to the sender: 
            Mail from (hacked) home based cable & dsl is rejected.
            Use a legitimate mail server!!