Mailinglist Archive: opensuse (3337 mails)

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Re: [SLE] mail sending and Postfix was OT: Posting from another unsubscribed address for a subscriber?
  • From: "Hylton Conacher (ZR1HPC)" <hylton@xxxxxxxxxxxx>
  • Date: Tue, 25 Apr 2006 12:18:22 +0200
  • Message-id: <444DF76E.3070000@xxxxxxxxxxxx>
Carlos E. R. wrote:

The Thursday 2006-04-20 at 13:08 +0200, Hylton Conacher (ZR1HPC) wrote:

So in essence, provided an individual/company uses the ISP of their domain
holder(ISP-1), they can use the ISP SMTP servers. If an individual/company
wants to obtain a domain at another ISP(ISP-2) and dial into ISP-1 to send
mail from the IAP2 domain, it is not 'allowed' to cut down on spam?

It depends on what rules the smtp server you want to use as relay server imposses on you. They can allow you, or not. Their choice.
Their choice has so far been to deny my use of the SMTP server for my domain mail.

There is something I am missing however :(
Something about the authentication :(

What hapens to folk who maintain their own SMTP servers(Postfix/Sendmail etc)?
Are they still restricted in sending mail from another another domain(ISP-2)
via a different ISP(ISP-1)?

If your provider is a good one they will not impede you from using their smtp as a relay server for all your email regardless of the from address you use.
From investigation my ISP SMTP server does not allow relays of mail from anoter domain other than the ones tey own.

Let me illustrate with an example on how I understand the SMTP process:

1. Assume that I had a two domains registered, each with a different

2. I have a single Postfix SMTP server for both domains, but I cannot
afford to keep it online 24/7 and so I have a dialup account with

3. On first dialup to ISP-1 my SMTP server authenticates and retrieves
its dynamic IP from ISP-1.

Nonononono. You get your IP much earlier that that, via ppp negotiation when the modem connects.
As I said when I first connect ie dialup.

It sends email to the server you have told it to send to. Distance or ownership has nothing to do. Nor has the smtp server got to connect or disconect after or before you receive mail from the pop server(s).
So basically the server I enter as the Mozilla SMTP server receives the mail from me and sends it to the destination or next relay before the destination, no questions asked?

4. The mail received by ISP-1's SMTP server is marked as certified as
ISP-1 was able to confirm that the sender was someone who they knew
and who had dialed into the ISP-1 network. The message details from
the message sender do not matter as they came from an authenticated
source. If there is a problem with one of the messages sent then
ISP-1 will be able to identify me as the sender and I could face
legal action.

I'm sorry, but I do not understand a word of what you are saying. Please, study the subject in manuals and howtos available in the distro, then explain again.
I'll browse the manuals but in essence 4. was dealing with authentication ie if mail is received by any SMTP server, is authentication done to ensure the mail came from an email on the registered domain.

I already explained what you needed to know, but what you say doesn't make any sense. Or I'm thick headed today, sorry.
I appreciate your assistance Carlos and I would rather be labelled the thick headed one in this discussion, as you are by no means, with the explanations given, the thick headed one. Perhaps I am not explaining it right or you are not understanding my explanations as I think you should. No fault of yours.

Let me try again... when you send email by any method using any relay server you hired, because it belongs to your isp, that email can be traced back to you regardless of your from address, and regardless of the method you used to authenticate yourself to the isp or smtp server - provided everything is correctly configured at their end.

This relay server will normally send all that email direct to the destination address, no intermediaries. The destination server can not do authentification, because the email is for him: he can not reject it, unless he thinks it is spam or virus or such.
AAAAHHHH Right, my thick headedness has cleared considerably! :)
I thought there were intermediaries as if a link to a country goes down then the packet would need to be routed to on another path via an intermediary host.

I thought the intermediary and destination server did authentication to cut back on SPAM.

OK, what I have managed to so far partly confirm is that my ISP is currently doing authentication on email the SMTP server receives from the ISPs users and thus they are prohibiting me from sending email from my own domain that is not held/registered by them, eventhough I hold a dialup and different email account with them.

Time to move ISP's

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