Afternoon All,
Not sure if it's new but FB's dmarc rejects as well. Noticed it when
someone tried to share something from FB with a mailing list.
_dmarc.facebook.com. 3600 IN TXT "v=DMARC1\; p=reject\;
pct=100\; rua=mailto:[email protected],mailto:[email protected]\;
ruf=mailto:[email protected]\;";
_dmarc.facebookmail.com. 2101 IN TXT "v=DMARC1\; p=reject\;
pct=100\; rua=mailto:[email protected],mailto:[email protected]\;
ruf=mailto:[email protected]\;";
Here's the current version of the code we are using to intervene for
mailing lists. It's more generic and does a dmarc lookup each time.
to use it, filter_initialize needs use Net::DNS;
Then in filter_end, we use this block:
#DMARC MAILING LIST RESOLUTION
foreach $recip (@Recipients) {
# BLOCK IF FROM YAHOO (AND OTHERS) BECAUSE THEY SET DMARC TOO
STRICTLY
#
http://www.pcworld.com/article/2141120/yahoo-email-antispoofing-policy-breaks-mailing-lists.html
# If Sender is set to DMARC reject and recipient is a mailing
list - NOTE Yahoo.com and AOL.com reject as of 4/23
if (($recip =~ m/\@mailman\./i or
(logic you add for your setup)
and
# exclude the admnistrivia addresses like admin confirm, join,
leave, etc.
($recip !~
/\-(admin|bounces|confirm|join|leave|owner|request|subscribe|unsubscribe)\@/i)
) {
my ($container, $parser, $original, $report2,
$dmarc_reject_notice, $sender, $dmarc_result, $sender_domain,
$modification_subject);
# Automatically check DMARC DNS entry
$sender_domain = &get_domain_from_email($Sender);
# DNS test for DMARC entry with timeout of 5 seconds
$dmarc_result = &check_dmarc(domain=>$sender_domain, timeout=>5);
if ($dmarc_result =~ /p=(reject|quarantine)/i) {
# NOTIFY SENDER AND REWRITE THE SENDER TO A DO-NOT-REPLY ADDRESS
md_syslog('warning', "Modifying message to mailing list due
to DMARC - $recip - $Sender - $Subject");
$dmarc_reject_notice = "Your email to $recip was modified due
to a change your email provider implemented which causes your email on
mailing lists to be flagged incorrectly as a forgery.
In order to permit your email through to the mailing list, we have
rewritten the From address to a do-not-reply address. Depending on the
list configuration, you may not receive replies and will need to monitor
the list. Additionally, this may delay your email as it will require
manual intervention by the list moderator to approve.
We apologize for the inconvenience but the cause of the issue rests
squarely and solely on your email provider. We recommend you consider a
free Google account available at http://www.gmail.com/. For more
technical information, please see:
http://www.pcworld.com/article/2141120/yahoo-email-antispoofing-policy-breaks-mailing-lists.html
and
http://postmaster-blog.aol.com/2014/04/22/aol-mail-updates-dmarc-policy-to-reject/
Sincerely,
Kevin A. McGrail
President, PCCC";
#CUSTOMIZE NOTIFICATION PARAMS
$sender = '[email protected]';
$modification_subject = "Important Mailing List Notification
re:[$Subject]";
#SEND NOTIFICATION
action_notify_sender_immediately(Sender=>$Sender,
DaemonName=>'PCCC Notice', DaemonAddress=>$sender,
NotifySenderSubject=>$modification_subject, body=>$dmarc_reject_notice);
#TEMPORARILY REMOVE MAILING LIST
#delete_recipient($recip); - NO LONGER NEEDED WITH REWRITE OF
FROM
#Possible Improvement is to do a DKIM/SPF/etc. check on the
email before rewriting to minimize forgeries getting farther in the process.
#CHANGE SENDER ON ENVELOPE
change_sender($sender);
#CHANGE SENDER ON FROM
if (&check_header(header=>'From')) {
action_delete_all_headers('From');
action_delete_all_headers('Reply-To');
action_add_header("From","\"DMARC Modified Email\" <$sender>");
action_add_header("Reply-To", "$Sender");
}
}
}
}
#END DMARC MAILING LIST HANDLING
You will also need these functions:
# check the HEADERS file and return any instances of a specific
parameter header (case insensitive on header name)
sub check_header {
my (%params) = @_;
my ($filehandle, $preslurp, $contents, $output);
$params{'header'} || return undef;
$filehandle = new IO::File('< ./HEADERS') or return undef;
while (<$filehandle>) {
if ($_ =~ /^$params{'header'}:/i) {
$output .= $_;
}
}
close ($filehandle);
return $output;
}
sub action_notify_sender_immediately {
my (%params) = @_;
my ($body, $recip);
# Send notification to sender - Based on function from mimedefang.pl
if ($params{'Sender'} ne '<>') {
$body = "From: $params{'DaemonName'} <$params{'DaemonAddress'}>\n";
$body .= "To: $params{'Sender'}\n";
$body .= gen_date_msgid_headers();
$body .= "Auto-Submitted: auto-generated\n";
$body .= "MIME-Version: 1.0\nContent-Type: text/plain\n";
$body .= "Precedence: bulk\n";
$body .= "Subject: $params{'NotifySenderSubject'}\n\n";
$body .= "$params{'body'}\n";
send_mail($params{'DaemonAddress'}, $params{'DaemonName'},
$params{'Sender'}, $body);
}
}
sub check_dmarc {
my (%params) = @_;
my ($res, $packet, @answer);
$res = Net::DNS::Resolver->new;
$params{'timeout'} ||= 10;
$params{'domain'} || return undef;
if (defined ($res)) {
$res->tcp_timeout($params{'timeout'}); #Number of Seconds
before query will fail
$res->udp_timeout($params{'timeout'}); #Number of Seconds
before query will fail
$packet = $res->query("_dmarc.$params{'domain'}","TXT","IN");
#Parse the Query
if (defined ($packet)) {
if (defined ($packet->answer)) {
@answer = $packet->answer;
if ($answer[0]->type eq "TXT") {
return $answer[0]->txtdata;
}
}
}
}
return undef;
}
#get domain name from an email address
sub get_domain_from_email {
my ($domain) = @_;
#REMOVE ANY LEADING/TRAILING <>'s
$domain =~ s/(^<|>$)//g;
#REMOVE ANY LEADING/TRAILING SPACE'S
$domain =~ s/^ *//g;
$domain =~ s/ *$//g;
#REMOVE EVERYTHING UP TO THE @ SYMBOL
$domain =~ s/.*\@//g;
return $domain;
}
regards,
KAM
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