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: "Carlos E. R." <robin.listas@xxxxxxxxxxxxxx>
  • Date: Wed, 26 Apr 2006 01:49:48 +0200 (CEST)
  • Message-id: <Pine.LNX.4.61.0604260059590.5889@xxxxxxxxxxxxxxxx>
Hash: SHA1

The Tuesday 2006-04-25 at 12:18 +0200, Hylton Conacher (ZR1HPC) wrote:


> > 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?

The first SMTP sever may ask questions, of course. Any SMTP server in the
chain, except the one of the destination address may ask for
authentication of some sort; ie, your ISP SMTP server may ask for it,
because it will _relay_ your mail to somebody else. Also, if to tell
Mozilla to send the email you write on the gmail account through gmail
smtp server (bypassing your ISP smtp server), this will also request some

It would be rare that the second server asked for ID, but it could happen:
for instance, in a private network users send to a certain local SMTP
server. This one sends to another one on their ISP, who request auth from
the private server (but not from the user: that is impossible).

The method used for authentication varies. An ISP can simply validate by
the IP number you use. Or, it can also see that you retrieved email from
them, say, three minutes ago from this IP (POP before SMTP). Or it can ask
for a login/password pair.

In other words: SMTP servers that relay email to some other smtp server
should normally use some kind of authentications. Those servers of the
destination address will not.

Another clarification: The minimum is two smtp servers in the chain. One
gets the email from you, the other one receives it for the addressee.
Depending on the setup, there can be intermediaries on both sides. Each
one normally adds a "Received" header to the email, and you can read them
(try: it is instructive).

> > 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.

No, intermediaries happens in complex setups for reasons different that
distance. But there might be none at all.

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

No, they do other kinds of tests, but they can not ask a login/password
from you, they doesn't "see" you.

> 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.

Right! :-)

> Time to move ISP's

There are more than one way. That's not the only possibility.

- --
Carlos Robinson
Version: GnuPG v1.4.0 (GNU/Linux)
Comment: Made with pgp4pine 1.76


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