Re: postfix for 2 domains on 1 vps 1 ip

[Brett Lymn <blymn%internode.on.net@localhost>]

On Sat, Jan 02, 2021 at 09:51:48PM -0700, Bob Proulx wrote:
> Brett Lymn wrote:
> > Bob Proulx wrote:
> > > SPF identifies authorized IP addresses for domains in the message
> > > envelope.  Therefore the reverse DNS pointer record does not matter in
> > 
> > I used to be postmaster for a large organisation and know for a fact that even if
> > you have SPF and DKIM set up properly there are still places on the internet that
> > will insist on the forward/reverse check and reject the mail if the addresses don't
> > match.  I can't give specific examples, I cannot remember, but they exist so keep an
> > eye out for rejected mails.
> 
> I wish you had not quoted the SPF bit when talking about forward
> reverse DNS checks but had instead quoted the bit where I talked about
> forward reverse DNS.  Because it leads me to believe that you think it
> is somehow related to SPF checks instead.  And as far as I know the
> forward reverse DNS issue is not in any way related to SPF.
> 

No I am not confused about what SPF does.  I was picking up on what you said:

 "Therefore the reverse DNS pointer record does not matter in"

that is true in the context of SPF but as I said not everyone does that, there are
sites out there that will do the forward/reverse validation.

> 
> Right.  There are sites that will require this.  They will tend to be
> the smaller sites that set something up in 2003 and are still running
> the same configuration now.  Mostly running MS Windows Server 2000 or
> some such platform.  It is generally not going to be a default action
> for new sites.  I don't think any of the large mailbox providers
> require it.
> 

It really doesnt matter why they are doing it, just that they do.  If you are trying
to communicate with these people then it becomes a real issue if they are rejecting
your emails.  It is common enough that we were getting complaints at $WORK about
rejected emails when our reverse lookups were broken.

-- 
Brett Lymn
--
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