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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Hi JP<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I think you misunderstand, we do not want to filter at the
exchange server, we only want to tag outgoing mail. So if we stamp outgoing
mail on the exchange server, the mailscanner servers can reject backscatter by
checking for valid watermarks. The backscatter never reaches the exchange
servers in that case.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>So we will leave all the filtering to the MS installation, we
just enhanve the options for filtering out mail by giving MS more things to
check for. Ie the watermark.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif";color:windowtext'>From:</span></b><span lang=EN-US
style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>
mailscanner-bounces@lists.mailscanner.info
[mailto:mailscanner-bounces@lists.mailscanner.info] <b>On Behalf Of </b>Koopmann,
Jan-Peter<br>
<b>Sent:</b> 26. maj 2008 11:14<br>
<b>To:</b> MailScanner discussion<br>
<b>Subject:</b> RE: Mailscanner watermarks and compatibility with other systems<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'>> </span><span lang=EN-US style='font-size:11.0pt;font-family:
"Calibri","sans-serif";color:#1F497D'>Obviously some will say “… just send
outgoing through MailScanner or similar system” but for some of us that’s
simply isn’t the smartest/best way to go about fighting backscatter. So for us
the event sink/transport agent method is brilliant and right on the spot.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'>Well obviously you have good reasons for doing what you are
doing. However one problem persists: If you discard all the backscatter at the
Exchange level it means you already accepted all the crap on your gateway,
scanned it for spam and viruses and then transport it to your customer. Once
you face a really big backscatter attack you will see that this is a big
problem. Moreover: Please make sure your Exchange plugin does not simply reject
the mail. This would be brilliant in case Exchange received the mail in the
first place but that is not the case in your scenario. If you accept the mail
and then later on Exchange chooses to reject the mail, you might in turn create
backscatter yourself.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'>Regards,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'> JP<o:p></o:p></span></p>
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