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Re: Federated, decentralised communication on the internet (was: domain names, was: hostname)

From Joe <joe@jretrading.com>
Newsgroups linux.debian.user
Subject Re: Federated, decentralised communication on the internet (was: domain names, was: hostname)
Date 2018-03-21 22:00 +0100
Message-ID <vvSZX-749-1@gated-at.bofh.it> (permalink)
References (6 earlier) <vmoeK-6AP-11@gated-at.bofh.it> <vvxC9-1Ii-7@gated-at.bofh.it> <vvyoy-24f-1@gated-at.bofh.it> <vvS3T-6qV-1@gated-at.bofh.it> <vvSwV-6QX-1@gated-at.bofh.it>
Organization JRE Trading Ltd

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On Wed, 21 Mar 2018 16:21:44 -0400
Greg Wooledge <wooledg@eeg.ccf.org> wrote:

> On Wed, Mar 21, 2018 at 02:53:47PM -0500, David Wright wrote:
> >       HELO dotlessdomainname
> >       HELO dotcontaining.home
> > 
> > I want someone to explain to me why having a dot is better then not
> > having a dot in deciding whether a submitter is genuine. And
> > without the politics.  
> 
> My understanding: the SMTP receiver will use whatever heuristics it
> finds appropriate to avoid receiving spam.

Indeed. Exim4 is fairly easy to configure either way.
> 
> One heuristic that is commonly used is to reject all messages where
> the HELO doesn't even syntactically qualify as a valid FQDN -- in
> other words, has no dot in it.
> 
> Another heuristic that is commonly used is to perform a DNS query on
> the HELO string, and reject it if it's not a valid FQDN based on DNS.
> 
> The first heuristic is much less expensive to perform, as it does not
> involve sending a DNS query and waiting for the response.  The test
> is simply a syntactic scan of the input string that it already has.
> 

I'm willing to do DNS lookups. Both the HELO and the PTR record of the
sending IP address need to be resolvable in public DNS for my mail
server to accept mail, as does the domain of the 'envelope' sender. The
latter weeds out a fair bit of spam.

> 
> For the person who is trying to send legitimate outgoing mail,
> obviously you don't want your messages to be rejected as spam.  So it
> behooves you to make sure your message complies with not only the
> applicable standards (SMTP = RFC 2821, etc.), but also with the known
> practices of potential receivers.  Which means, among other things,
> having a HELO string that won't cause your message to be dropped as
> probable spam.
> 

I haven't done it recently, but I often used to use a telnet connection
to talk manually to many SMTP servers, most of them required a
resolvable HELO, but they didn't care if it had any connection with the
sender. To minimise typing, I used to use a six-character domain name
(there are several) to which I had no rights whatever. 

I've seen one of my clients' Exchange servers reject a connection from
BT, the UK telecoms provider, because one of its Exchange servers was
misconfigured to send its own private domain name, with a .local TLD,
as its HELO.

-- 
Joe

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Thread

hostname bolakim53@mail2tor.com - 2018-02-15 15:30 +0100
  Re: hostname Greg Wooledge <wooledg@eeg.ccf.org> - 2018-02-15 15:40 +0100
    Re: hostname Dan Purgert <dan@djph.net> - 2018-02-15 17:40 +0100
      Re: domain names, was: hostname Jeremy Nicoll <jn.ml.dbn.25@letterboxes.org> - 2018-02-19 13:30 +0100
        Re: domain names, was: hostname Dan Purgert <dan@djph.net> - 2018-02-19 14:50 +0100
          Re: domain names, was: hostname Jeremy Nicoll <jn.ml.dbn.25@letterboxes.org> - 2018-02-20 20:40 +0100
            Re: domain names, was: hostname Greg Wooledge <wooledg@eeg.ccf.org> - 2018-02-20 20:50 +0100
              Re: domain names, was: hostname Jeremy Nicoll <jn.ml.dbn.25@letterboxes.org> - 2018-02-20 21:00 +0100
            Re: domain names, was: hostname Dan Purgert <dan@djph.net> - 2018-02-21 01:20 +0100
            Re: domain names, was: hostname mick crane <mick.crane@gmail.com> - 2018-02-21 01:30 +0100
              Re: domain names, was: hostname Dan Purgert <dan@djph.net> - 2018-02-21 01:50 +0100
                Re: domain names, was: hostname Glenn English <ghe2001@gmail.com> - 2018-02-21 02:10 +0100
                Re: domain names, was: hostname mick crane <mick.crane@gmail.com> - 2018-02-21 02:10 +0100
                Re: domain names, was: hostname Reco <recoverym4n@gmail.com> - 2018-02-21 07:10 +0100
                Re: domain names, was: hostname Darac Marjal <mailinglist@darac.org.uk> - 2018-02-21 11:30 +0100
                Re: domain names, was: hostname Dan Purgert <dan@djph.net> - 2018-02-21 13:50 +0100
                Re: domain names, was: hostname Reco <recoverym4n@gmail.com> - 2018-02-21 13:50 +0100
                Re: domain names, was: hostname Gene Heskett <gheskett@shentel.net> - 2018-02-21 13:00 +0100
                Re: domain names, was: hostname Reco <recoverym4n@gmail.com> - 2018-02-21 13:50 +0100
                Re: domain names, was: hostname Curt <curty@free.fr> - 2018-02-21 16:40 +0100
                Re: domain names, was: hostname Frank <zuiderduin@gmx.com> - 2018-02-23 21:00 +0100
        Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-02-19 17:30 +0100
          Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-02-19 19:40 +0100
            Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-02-22 19:00 +0100
              Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-02-23 14:00 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-02-24 04:50 +0100
                Re: domain names, was: hostname Curt <curty@free.fr> - 2018-02-26 11:50 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-02-26 19:00 +0100
              Re: domain names, was: hostname Dan Purgert <dan@djph.net> - 2018-02-23 14:10 +0100
                Re: domain names, was: hostname Joe <joe@jretrading.com> - 2018-02-23 18:10 +0100
                Re: domain names, was: hostname mick crane <mick.crane@gmail.com> - 2018-03-21 17:20 +0100
              Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-02-23 17:20 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-03-20 23:10 +0100
                Federated, decentralised communication on the internet (was: domain names, was: hostname) Ben Finney <bignose@debian.org> - 2018-03-21 00:00 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) Forest Dean Feighner <forest.feighner@gmail.com> - 2018-03-21 00:20 +0100
                Re: Federated, decentralised communication on the internet (was: domain names, was: hostname) deloptes <deloptes@gmail.com> - 2018-03-21 22:10 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) Forest Dean Feighner <forest.feighner@gmail.com> - 2018-03-21 22:10 +0100
                Re: Federated, decentralised communication on the internet (was: domain names, was: hostname) deloptes <deloptes@gmail.com> - 2018-03-21 22:30 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) Forest <forest.feighner@gmail.com> - 2018-03-22 01:40 +0100
                Re: Federated, decentralised communication on the internet (was: domain names, was: hostname) deloptes <deloptes@gmail.com> - 2018-03-22 21:40 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) <tomas@tuxteam.de> - 2018-03-21 09:10 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) terryc <terryc@woa.com.au> - 2018-03-21 10:40 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) "Michelle Konzack" <linux4michelle@tamay-dogan.net> - 2018-03-22 07:30 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) Celejar <celejar@gmail.com> - 2018-03-23 19:00 +0100
                Re: Federated, decentralised communication on the internet Charlie Gibbs <cgibbs@surfnaked.ca> - 2018-03-21 16:50 +0100
                Re: Federated, decentralised communication on the internet Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-21 17:10 +0100
                Re: Federated, decentralised communication on the internet Richard Owlett <rowlett@cloud85.net> - 2018-03-21 17:40 +0100
                Re: Federated, decentralised communication on the internet Gene Heskett <gheskett@shentel.net> - 2018-03-21 18:00 +0100
                Re: Federated, decentralised communication on the internet Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-21 21:40 +0100
                Re: Federated, decentralised communication on the internet Richard Owlett <rowlett@cloud85.net> - 2018-03-21 22:30 +0100
                Re: Federated, decentralised communication on the internet Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-21 23:00 +0100
                Re: Federated, decentralised communication on the internet Richard Owlett <rowlett@cloud85.net> - 2018-03-21 23:30 +0100
                Re: Federated, decentralised communication on the internet Dan Purgert <dan@djph.net> - 2018-03-22 01:10 +0100
                Re: Federated, decentralised communication on the internet Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-22 01:10 +0100
                Re: Federated, decentralised communication on the internet Brian <ad44@cityscape.co.uk> - 2018-03-21 21:50 +0100
                Re: Federated, decentralised communication on the internet Richard Owlett <rowlett@cloud85.net> - 2018-03-21 22:50 +0100
                Re: Federated, decentralised communication on the internet Brian <ad44@cityscape.co.uk> - 2018-03-21 23:50 +0100
                Re: Federated, decentralised communication on the internet Darac Marjal <mailinglist@darac.org.uk> - 2018-03-22 09:40 +0100
                Re: Re: Federated, decentralised communication on the internet dekks herton <dekkzz78@gmail.com> - 2018-03-23 00:10 +0100
                Re: Federated, decentralised communication on the internet Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-23 01:50 +0100
                Re: Federated, decentralised communication on the internet deloptes <deloptes@gmail.com> - 2018-03-21 22:30 +0100
                Re: Federated, decentralised communication on the internet (was: domain names, was: hostname) deloptes <deloptes@gmail.com> - 2018-03-21 22:20 +0100
                Re: Federated, decentralised communication on the internet Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-22 00:40 +0100
                Re: Federated, decentralised communication on the internet deloptes <deloptes@gmail.com> - 2018-03-22 09:00 +0100
                Re: Federated, decentralised communication on the internet Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-22 15:00 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) David Wright <deblis@lionunicorn.co.uk> - 2018-03-21 21:00 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) Greg Wooledge <wooledg@eeg.ccf.org> - 2018-03-21 21:30 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) Joe <joe@jretrading.com> - 2018-03-21 22:00 +0100
                Re: Federated, decentralised communication on the internet (was: domain names, was: hostname) deloptes <deloptes@gmail.com> - 2018-03-21 22:40 +0100
                Re: Federated, decentralised communication on the internet (was: domain names, was: hostname) deloptes <deloptes@gmail.com> - 2018-03-21 22:40 +0100
                Re: Federated, decentralised communication on the internet Richard Hector <richard@walnut.gen.nz> - 2018-03-21 23:10 +0100
                Re: Federated, decentralised communication on the internet Dan Purgert <dan@djph.net> - 2018-03-22 01:20 +0100
                Re: Federated, decentralised communication on the internet Greg Wooledge <wooledg@eeg.ccf.org> - 2018-03-22 13:20 +0100
                Re: Federated, decentralised communication on the internet Richard Hector <richard@walnut.gen.nz> - 2018-03-22 23:10 +0100
                Re: Federated, decentralised communication on the internet Dan Purgert <dan@djph.net> - 2018-03-22 23:50 +0100
                Re: Federated, decentralised communication on the internet Richard Hector <richard@walnut.gen.nz> - 2018-03-23 00:20 +0100
                Re: Federated, decentralised communication on the internet Dan Purgert <dan@djph.net> - 2018-03-23 02:10 +0100
                Re: Federated, decentralised communication on the internet Richard Hector <richard@walnut.gen.nz> - 2018-03-23 04:00 +0100
                Re: Federated, decentralised communication on the internet Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-23 02:50 +0100
                Re: Federated, decentralised communication on the internet Richard Hector <richard@walnut.gen.nz> - 2018-03-23 04:10 +0100
                Re: Federated, decentralised communication on the internet Greg Wooledge <wooledg@eeg.ccf.org> - 2018-03-23 13:30 +0100
                Re: Federated, decentralised communication on the internet Phil Dobbin <bukowskiscat@gmail.com> - 2018-03-23 15:10 +0100
                Re: Federated, decentralised communication on the internet Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-23 17:50 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) David Wright <deblis@lionunicorn.co.uk> - 2018-03-22 01:00 +0100
                Re: Federated, decentralised communication on the internet (was: domain names, was: hostname) deloptes <deloptes@gmail.com> - 2018-03-22 09:20 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) Joe <joe@jretrading.com> - 2018-03-22 09:50 +0100
                Re: Federated, decentralised communication on the internet (was:  domain names, was: hostname) Greg Wooledge <wooledg@eeg.ccf.org> - 2018-03-22 14:00 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-03-22 18:50 +0100
                Re: domain names, was: hostname Greg Wooledge <wooledg@eeg.ccf.org> - 2018-03-22 19:10 +0100
                Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-03-22 21:30 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-03-23 03:10 +0100
                Re: domain names, was: hostname Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-23 17:00 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-03-23 18:10 +0100
                Re: domain names, was: hostname Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-23 18:10 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-03-24 01:50 +0100
                Re: domain names, was: hostname Miles Fidelman <mfidelman@meetinghouse.net> - 2018-03-24 14:00 +0100
                Re: domain names, was: hostname "Michelle Konzack" <linux4michelle@tamay-dogan.net> - 2018-03-24 14:10 +0100
                Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-03-23 20:20 +0100
                Re: domain names, was: hostname rhkramer@gmail.com - 2018-03-23 21:10 +0100
                Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-03-23 21:30 +0100
                Re: domain names, was: hostname Michael Stone <mstone@debian.org> - 2018-03-24 02:30 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-03-24 02:10 +0100
                Re: domain names, was: hostname Joe <joe@jretrading.com> - 2018-03-23 23:30 +0100
                Re: domain names, was: hostname Forest <forest.feighner@gmail.com> - 2018-03-23 23:50 +0100
                Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-03-24 00:00 +0100
                Re: domain names, was: hostname rhkramer@gmail.com - 2018-03-24 01:20 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-03-24 02:20 +0100
                Re: domain names, was: hostname rhkramer@gmail.com - 2018-03-24 02:40 +0100
                Re: domain names, was: hostname Dan Purgert <dan@djph.net> - 2018-03-22 23:30 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-03-23 03:50 +0100
                Re: domain names, was: hostname Dan Purgert <dan@djph.net> - 2018-03-23 11:50 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-03-23 16:50 +0100
                Re: domain names, was: hostname Greg Wooledge <wooledg@eeg.ccf.org> - 2018-03-23 17:00 +0100
                Re: domain names, was: hostname Dan Purgert <dan@djph.net> - 2018-03-23 18:50 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-03-23 20:00 +0100
                Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-03-23 21:10 +0100
                Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-03-21 00:10 +0100
                Re: domain names, was: hostname Richard Hector <richard@walnut.gen.nz> - 2018-03-21 04:40 +0100
                Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-03-21 18:30 +0100
                Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-03-21 21:10 +0100
                Re: domain names, was: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-03-22 02:10 +0100
        Re: domain names, was: hostname Brad Rogers <brad@fineby.me.uk> - 2018-02-19 18:30 +0100
          Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-02-19 20:00 +0100
            Re: domain names, was: hostname Brad Rogers <brad@fineby.me.uk> - 2018-02-19 20:20 +0100
              Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-02-19 20:30 +0100
                Re: domain names, was: hostname Joe <joe@jretrading.com> - 2018-02-19 21:40 +0100
                Re: domain names, was: hostname Brian <ad44@cityscape.co.uk> - 2018-02-19 21:50 +0100
                Re: domain names, was: hostname Roberto C. Sánchez <roberto@debian.org> - 2018-02-19 22:00 +0100
                Re: domain names, was: hostname rhkramer@gmail.com - 2018-02-19 22:20 +0100
                Re: domain names, was: hostname Reco <recoverym4n@gmail.com> - 2018-02-19 22:00 +0100
    Re: hostname deloptes <deloptes@gmail.com> - 2018-02-15 19:10 +0100
    Re: hostname Nicholas Geovanis <nickgeovanis@gmail.com> - 2018-02-15 20:50 +0100
      Re: hostname Gene Heskett <gheskett@shentel.net> - 2018-02-15 21:40 +0100
        Re: hostname Nicholas Geovanis <nickgeovanis@gmail.com> - 2018-02-15 23:30 +0100
        Re: hostname Nicholas Geovanis <nickgeovanis@gmail.com> - 2018-02-15 23:50 +0100
          Re: hostname Gene Heskett <gheskett@shentel.net> - 2018-02-16 01:30 +0100
          Re: hostname deloptes <deloptes@gmail.com> - 2018-02-16 07:50 +0100
        Re: hostname Dan Purgert <dan@djph.net> - 2018-02-16 00:50 +0100
      Re: hostname deloptes <deloptes@gmail.com> - 2018-02-15 22:20 +0100
    Re: hostname Nicholas Geovanis <nickgeovanis@gmail.com> - 2018-02-15 20:50 +0100
    Re: hostname David Wright <deblis@lionunicorn.co.uk> - 2018-02-16 00:20 +0100
      Re: hostname Dan Purgert <dan@djph.net> - 2018-02-16 01:00 +0100
    hostname Jonathan de Boyne Pollard <J.deBoynePollard-newsgroups@NTLWorld.COM> - 2018-02-18 09:10 +0100
      Re: hostname Reco <recoverym4n@gmail.com> - 2018-02-18 09:50 +0100

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