[Mimedefang] Can MD/SA combo detect no reverse ip?

[Joseph Brennan]

--On Thursday, June 12, 2003 07:22 -0400 "G. Roderick Singleton" 
<gerry at pathtech.org> wrote:

> I have been watching my logs for the past few days and find that there
> is a bunch o' spam that gets trough with SA scores of less than the 5
> threshold I use and most of these don't resolve to a reverse address
> that is authoritative. I would like to block these and if possible block
> dns lamers.

You'd be rejecting a lot of non-spam mail.  Some of the MSN mail
servers lack reverse DNS, as an example; so do miscellaneous
nonprofits and small businesses.  Remember the RFCs do not require
rDNS for mail hosts.

But you could add to the spam score.

In filter_begin()

    # Spamassassin tweaks using relay information
    $SA_score_additions = 0;
    $SA_test_additions = "";

    # Prejudice against no rDNS
    if ($RelayHostname =~ /\[$RelayAddr\]/) {
        $SA_score_additions += 2;
        $SA_test_additions .= ",NO_RDNS";
    }


In filter_end(), add the score and test name right after you run
Spamassassin, like this.

            my($hits, $req, $names, $report) = spam_assassin_check();

            # add our things
            $hits += $SA_score_additions;
            $names .= $SA_test_additions;


The reason I did it this way was to use the $RelayHostname
and $RelayAddr values that we get in Mimedefang.

Adding 2 is enough for us.

Joseph Brennan          Columbia University in the City of New York
postmaster at columbia.edu                 Academic Technologies Group