milter-ns

A Milter to block Email based on the sending domain's Name Server Copyright (c) 2014, Montagar Software, Inc.

As I've been getting more SPAM lately, I was trying to figure out a way to stop more of it. Looking at the domains, they were all using "Privacy Protection" and often registered via Moniker. Then Moniker seemed to get tired of them and they moved to ENOM as a Registrar. Often the domains where registered the same day of the spam.

The common item was they were always using ENOM as the Name Server for the domain. So if the only mail I'm getting from ENOM registered domain is SPAM, I can just write a milter to get the HELO/EHLO and MAILFROM information, check the Name Server for that domain, and fail the transaction if it's using their name servers.

It seems pretty effective, as SPAM that gets by the RBL's has dropped considerably.

Licensing

See COPYING for license information.

Prerequisites

    sendmail

Installation

    ./configure --prefix=/usr

    Add a similar line to /etc/mail/sendmail.mc:
    INPUT_MAIL_FILTER(`mymilter', `S=unix:/var/run/milter-ns.sock, T=S:30s;R:30s;E:5m')

    Rebuild sendmail.cf, and restart:
    make
    systemctl restart sendmail

    Add the folling file to /etc/init:

    milter-ns.conf

    This file will insure the milter is started before sendmail is started