<HTML dir=ltr><HEAD><TITLE>Re: better blocking at MTA level (off-topic)</TITLE>
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<DIV dir=ltr><FONT face=Arial color=#000000 size=2>The problem with greylisting as we found when we enabled it was that some MTA's treat a temporary reject code (450) as a permanent reject code (550) and our customer was complaining that they weren't getting email. Whilst we could exempt every MTA they flag up to us from greylisting checking there is no way to prevent email from an unknown source getting blocked and not getting through to them. Until we can resolve the problem without telling our customer to tell anyone emailing them with problems to get their MTA fixed it unfortunately has to be off... It did vastly reduce the load on our server whilst greylisting was active though.</FONT></DIV>
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<DIV dir=ltr><FONT face=Arial size=2>The hit of the first email being delayed for the 5 minutes we initially chose was insignificant and no-one would really notice... </FONT></DIV>
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<DIV dir=ltr><FONT face=Arial size=2>Jason</FONT></DIV></DIV>
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<FONT face=Tahoma size=2><B>From:</B> mailscanner-bounces@lists.mailscanner.info on behalf of Sergio Rabellino<BR><B>Sent:</B> Sat 26/05/2007 12:03<BR><B>To:</B> MailScanner discussion<BR><B>Subject:</B> Re: better blocking at MTA level (off-topic)<BR></FONT><BR></DIV>
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<P><FONT size=2>I'm very happy about greylisting.<BR>I introduced it (smf grey -sendmail filter) one week ago and the spam<BR>shrinks by 90%.<BR>Obviously we could/would pay the delay of the "first" email against the very<BR>high reduction of the spam.<BR>Also my server runqueue goes from "uptime 8" to "uptime 0.6", more cpu for<BR>other jobs....<BR><BR>Bye.<BR>----- Original Message -----<BR>From: "Koopmann, Jan-Peter" <jan-peter@koopmann.eu><BR>To: "MailScanner discussion" <mailscanner@lists.mailscanner.info><BR>Sent: Saturday, May 26, 2007 10:17 AM<BR>Subject: better blocking at MTA level (off-topic)<BR><BR><BR>Hi,<BR><BR>looking at todays 88% High Scoring Spam ratio I would like to block more<BR>at the MTA level. What are relyable RBL services (commercial is fine)<BR>that can be used? Or other methods besides tarpitting, pipelining tricks<BR>etc. at MTA level (which we all do) that would reduce the load?<BR><BR>Or am I the only one suffering from massive attacks the past few days?<BR>What are you guys using?<BR><BR><BR><BR>Kind regards<BR><BR>Jan-Peter Koopmann<BR><BR>--<BR>MailScanner mailing list<BR>mailscanner@lists.mailscanner.info<BR><A href="http://lists.mailscanner.info/mailman/listinfo/mailscanner">http://lists.mailscanner.info/mailman/listinfo/mailscanner</A><BR><BR>Before posting, read <A href="http://wiki.mailscanner.info/posting">http://wiki.mailscanner.info/posting</A><BR><BR>Support MailScanner development - buy the book off the website!<BR><BR>--<BR>MailScanner mailing list<BR>mailscanner@lists.mailscanner.info<BR><A href="http://lists.mailscanner.info/mailman/listinfo/mailscanner">http://lists.mailscanner.info/mailman/listinfo/mailscanner</A><BR><BR>Before posting, read <A href="http://wiki.mailscanner.info/posting">http://wiki.mailscanner.info/posting</A><BR><BR>Support MailScanner development - buy the book off the website!<BR></FONT></P></DIV></BODY><br />-----------------------------------------------------------
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