rblsmtpd 451 Sender has sent to LashBack

Bounce message received:

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

[email protected]

Malformed SMTP reply from mail.server.com [192168.1.1]
in response to initial connection:
rblsmtpd: pid 14483: 451 Sender has sent to LashBack
Unsubscribe Probe accounts:
retry timeout exceeded

Looking further into this it appears that the sending IP address was listed in a RBL black list.  The RBL server being queried was: ubl.unsubscore.com

This in turn (www.unsubscore.com) took me to: http://www.lashback.com/support/UnsubscribeBlacklistSupport.aspx

Most RBL systems return a useful message with a URL, but, not lashback.

Quick CLI SMTP AUTH script to test authentication

I was getting a bit bored of manually testing SMTP AUTH details for people so wrote a quick little script in perl (with help of modules) to test.

#!/usr/bin/perl -w

use Net::SMTP_auth;
use Getopt::Std;

test_auth.pl   -  Check SMTP authentication

Usage:   test_auth.pl -u user -p pass -h hostname

License: This software is released under the same terms as perl itself.


die $_USAGE unless ($options{u} && $options{p} && $options{h});

$smtp = Net::SMTP_auth->new($options{h});
if ( $smtp->auth(‘CRAM-MD5’, $options{u}, $options{p}) ) {
print “Authenticated…\n”;
} else {
print “Authentication failed…\n”;