smtpd_reject_unlisted_recipient
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From: Jerrale Gayle on 10 Jun 2010 17:51 smtpd_reject_unlisted_recipient = no Would this be better put by itself or under smtpd_recipient_restrictions = reject_unlisted_recipient=no? I want to accept all mail to non-existent users, then bounce, so that people can't probe for valid users to know wherer to start a brute force.
From: Sahil Tandon on 10 Jun 2010 18:31 On Thu, 10 Jun 2010, Jerrale Gayle wrote: > smtpd_reject_unlisted_recipient = no Bad idea. > Would this be better put by itself or under > smtpd_recipient_restrictions = reject_unlisted_recipient=no? Bad idea + unsupported syntax. > I want to accept all mail to non-existent users, then bounce, so > that people can't probe for valid users to know wherer to start a > brute force. This is a horrible idea; please do not do this. Google 'backscatter'. -- Sahil Tandon <sahil(a)FreeBSD.org>
From: Rod Dorman on 10 Jun 2010 18:30 On Thursday, June 10, 2010, 17:51:13, Jerrale Gayle wrote: > smtpd_reject_unlisted_recipient = no > > Would this be better put by itself or under smtpd_recipient_restrictions > = reject_unlisted_recipient=no? > > I want to accept all mail to non-existent users, then bounce, so that > people can't probe for valid users to know wherer to start a brute force. So when a spammer uses my e-mail address you'll send the bounce to me? Gee, thanks. -- rodd(a)polylogics.com "The avalanche has already started, it is too Rod Dorman late for the pebbles to vote." - Ambassador Kosh
From: Jerrale Gayle on 10 Jun 2010 19:17 On 6/10/2010 6:31 PM, Sahil Tandon wrote: > On Thu, 10 Jun 2010, Jerrale Gayle wrote: > > >> smtpd_reject_unlisted_recipient = no >> > Bad idea. > > >> Would this be better put by itself or under >> smtpd_recipient_restrictions = reject_unlisted_recipient=no? >> > Bad idea + unsupported syntax. > > >> I want to accept all mail to non-existent users, then bounce, so >> that people can't probe for valid users to know wherer to start a >> brute force. >> > This is a horrible idea; please do not do this. Google 'backscatter'. > > IF I have repeating undeliverable mail being redirected to postmaster(a)mydomain, I don't see why this would be a bad idea.
From: Sahil Tandon on 10 Jun 2010 20:49
On Thu, 10 Jun 2010, Jerrale Gayle wrote: > On 6/10/2010 6:31 PM, Sahil Tandon wrote: > >On Thu, 10 Jun 2010, Jerrale Gayle wrote: > > > >>smtpd_reject_unlisted_recipient = no > >Bad idea. > > > >>Would this be better put by itself or under > >>smtpd_recipient_restrictions = reject_unlisted_recipient=no? > >Bad idea + unsupported syntax. > > > >>I want to accept all mail to non-existent users, then bounce, so > >>that people can't probe for valid users to know wherer to start a > >>brute force. > >This is a horrible idea; please do not do this. Google 'backscatter'. > > > IF I have repeating undeliverable mail being redirected to > postmaster(a)mydomain, I don't see why this would be a bad idea. This is my last reply on this topic; from wikipedia: Backscatter occurs because worms and spam messages often forge their sender address, and mailservers configured by naive administrators send a bounce message to this address. -- Sahil Tandon <sahil(a)FreeBSD.org> |