Date: Sun, 18 Jan 1998 00:10:06 +0000 From: Thordur Ivarsson <totii@est.is> To: Dan Busarow <dan@dpcsys.com> Cc: Font <font@Mcs.Net>, questions@FreeBSD.ORG Subject: Re: MAIL FROM: address check commented out in /etc/mail additions? Message-ID: <34C1485E.977C0065@est.is> References: <Pine.UW2.3.95.980115101559.614D-100000@cedb>
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Dan Busarow wrote: > > On Thu, 15 Jan 1998, Font wrote: > > closer examination I found that a line in sendmail.cf.additions had been > > commented out: > > > > # R<?> $* < @ $+ > $#error $: "451 Domain does not resolve" > > > > I was just curious as to whether this was intentional (what are the > > disadvantages here? can some legit mail be rejected?) or just overlooked. > This rule is rather nasty: If sender has not legimate A record in name server the rule fails and sends back error, CNAME record is not enough for sender. > Can't tell you why the line is commented out but I can say that > since adding this our spam has gone *way* down. It catches several > hundred a day. More than any of the other anti-spam checks. > > I haven't checked in some time but I did monitor the logs closely > after installing it and only found one instance where it looked > like a legitimate, but misconfigured mailer. I contacted the > customer it was addressed to and asked if he knew how to get in > touch with the apparent sender and my customer said "those guys > have been spamming me" :) > > IOW, it really seems to work well. > -- Þórður Ívarsson Thordur Ivarsson Rafeindavirki Electronic technician Norðurgötu 30 Nordurgotu 30 Box 309 Box 309 602 Akureyri 602 Akureyri Ísland Iceland --------------------------------------------- FreeBSD has good features, Some others are full of unwanted features! ---------------------------------------------
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