[CentOS] Re: postfix tightening

Sat Apr 2 21:54:37 UTC 2005
Les Mikesell <lesmikesell at gmail.com>

On Sat, 2005-04-02 at 02:27, Tom Ivar Helbekkmo wrote:

> > Lets say that Acme Widget has their mail hosted with Hostco. Acme Widget
> > would rather not have mail.hostco.com in the mail headers for whatever
> > reason. So, hostco doesn't setup a ptr record for it. This does not make
> > Acme Widget or Hostco any more likely to be spammers, it just makes you
> > more likely to drop their mail.
> So they deliberately configure a non-compliant system, breaking the
> rules for connecting to the Internet, as set down in the RFCs? 

Please specify the requirement that you mean here.

>  Then
> they will have problems sending email to a large number of sites, and
> rightly so.  They need to fix their misconfigured email system.  This
> is not a matter of opinion: they've set it up *wrong*.
> Anyway, the point of checking that a system that's trying to deliver
> email to you has a name that resolves to the address it's using, that
> that address resolves back to the name, and that the HELO specifies
> the correct name as well, is that most privately owned Windows PCs
> don't fulfill those requirements.

There is no requirement for the HELO to match anything else.  It must
be syntactically correct but it does not have to have anything to do
with the particular interface you happen to be using.  On the other
hand the From: address does have to be resolvable - otherwise you
wouldn't be able to reply anyway.

  Les Mikesell
    les at futuresource.com