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<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=087283714-22102007>Paul
Houselander: I forgot to answer you your question, yes there are lots of
underivable messages, but they are not the most, the biggest portion of mails
stuck are spam, however underivable messages are a considerable number and
perhaps you are probably right and the server is under a backscatter attack.
I'll check the documentation you sent me. There is no doubt, I'll have
to implement a recipient checking at smtp level(as Jason has advised
me).</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV align=left>
<DIV align=left><FONT face=Arial size=2>
<DIV align=left><A href="http://www.cht.com.ar/"><FONT face=Verdana
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<DIV></DIV><FONT face=Tahoma size=2>-----Mensaje original-----<BR><B>De:</B>
mailscanner-bounces@lists.mailscanner.info
[mailto:mailscanner-bounces@lists.mailscanner.info] <B>En nombre de </B>Paul
Houselander<BR><B>Enviado el:</B> viernes, 19 de octubre de 2007
13:52<BR><B>Para:</B> MailScanner discussion<BR><B>Asunto:</B> RE: Weird Problem
with MailScanner<BR><BR></FONT></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=656494416-19102007>Were
lots of the messages undeliverable messages?</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=656494416-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=656494416-19102007>In
which case it could be your domain was under a backscatter attack see -
</SPAN></FONT><FONT face=Arial color=#0000ff size=2><SPAN
class=656494416-19102007><A
href="http://spamlinks.net/prevent-secure-backscatter.htm">http://spamlinks.net/prevent-secure-backscatter.htm</A></SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=656494416-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=656494416-19102007>Ive
had this happen to various customers where all of a sudden there incommg
e-mail shoots up to ridiculous levels.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=656494416-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=656494416-19102007>The
quickest form of defence would be to implement some sort of recipient
verification - I use mimedefang to achieve this here (sendmail). Before
sendmail accepts the e-mail it checks if the recipient is indeed a valid user
on your exchange box.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=656494416-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=656494416-19102007>You
need to be running at least Exchange 2003 and above and enable recipient
filtering <A
href="http://support.microsoft.com/kb/886208">http://support.microsoft.com/kb/886208</A></SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=656494416-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=656494416-19102007>If
the messages were not lots of undeliverable messages and all to valid
recipients I would agree with the other reply that your server sounds like it
needs an upgrade to cope.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=656494416-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=656494416-19102007>Cheers</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=656494416-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=656494416-19102007>Paul</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=656494416-19102007></SPAN></FONT> </DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
mailscanner-bounces@lists.mailscanner.info
[mailto:mailscanner-bounces@lists.mailscanner.info]<B>On Behalf Of
</B>Gareth<BR><B>Sent:</B> 19 October 2007 17:32<BR><B>To:</B> MailScanner
discussion<BR><B>Subject:</B> RE: Weird Problem with MailScanner {Scanned by
Allteks Mailsafe}<BR><BR></FONT></DIV>
<DIV><SPAN class=544243116-19102007><FONT face=Arial color=#0000ff size=2>I
would say it is seriously in need of a memory upgrade. The minimum
recomendation is 1GB.</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
mailscanner-bounces@lists.mailscanner.info
[mailto:mailscanner-bounces@lists.mailscanner.info]<B>On Behalf Of
</B>Damian Rivas<BR><B>Sent:</B> 19 October 2007 17:22<BR><B>To:</B>
mailscanner@lists.mailscanner.info<BR><B>Subject:</B> Weird Problem with
MailScanner<BR><BR></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>Hi there, I'm
having a really weird problem and as I am a n00b it gets a bit more
difficult to find a solution. </SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=725004715-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>I'll explain
the details first:</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=725004715-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>Since 6 months
ago, I am the System Administrator of a Tourism Agency. We use an E-mail
Scanner in a server with the following
characteristics:</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=725004715-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>Processor:
Pentium II 233 Mhz.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>RAM: 128
MB</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>OS: Linux
Slackware 9</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>MailScanner
version: 4.55.10</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=725004715-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>This E-mail
Scanner use the MailScanner with Sophos Antivirus and Spam Assasin to
filter spam and scan incoming and outcoming mails for viruses which are
then redirected to an internal MS Exchange Server or to the Internet,
respectively by sendmail.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=725004715-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>One month
ago, the server started behaving erratically. Instead of
checking and sending mails as it normally did, it started queueing mails
massively and therefore accumulating great quantities of them, it got up
to 10000 mails queued up in a single day, therefore, no one recieved
a single mail. After many pointless attempts to repair this problem and
seeing that the Travel Agents were getting a bit mad, I decided to
redirect the MX server of our domains in the DNS to the firewall, so that
our E-Mail Scanner server didn't recieve more mail, which was only going
to contribute to making the problem worse, more incoming mails,
more queued mails.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=725004715-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>With this, the
server started sending the queued mails and mail traffic was restored
with the difference that mails weren't scanned at all(they were no longer
passing through the MailScanner Server). When the mail queues were empty
again, I tried to reestablish the scanning service, but the problem
appeared again.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=725004715-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>I don't have a
clear idea of what can be causing this problem. The machine is pretty old,
but the former administrator told me that it had never had problems. I
think that perhaps we are being Spam Bombed and perhaps the System poor
processing capabilities cannot resists the increasing traffic and
therefore it gets stuck and keeps enqueueing mails.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=725004715-19102007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>Please if
anyone can guide me I'll appreciate it,</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>Sorry if my
English is a bit rusty, it is not my native language, therefore if you
need me to be more clear or try to give more details of something, don't
hesitate to ask so.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=725004715-19102007>Thanks in
advance!</SPAN></FONT></DIV>
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