[TriLUG] Fwd: mail relay through trilug.org?
lopaki at gmail.com
Tue Jul 10 14:21:47 EDT 2007
The Helo/Eloh chit chat. If you look at the actual interchange, it looks
the same whether the connecting machine is a client or a server or even a
human typing commands in a terminal.
It never says by the way I am a pine session so treat me like a punk.
On 7/10/07, Tanner Lovelace <clubjuggler at gmail.com> wrote:
> On 7/10/07, Scott Lambdin <lopaki at gmail.com> wrote:
> > On 7/10/07, Tanner Lovelace <clubjuggler at gmail.com> wrote:
> > >
> > > Port 587 - (See RFC2476). This is the mail submission port. It only
> > > takes
> > > incoming mail from mail clients, not mail servers. (I believe) You
> > > first do STARTTLS to encrypt the channel, then SMTP AUTH to log in
> > > and only then will it let you relay mail.
> > I think clients and servers are not distinguishable in smtp.
> No, you're not looking at it correctly. Postfix on ports 25 and 465 are
> as "Mail Transfer Agents" or MTAs. On port 587 it is acting as a "Mail
> Submission Agent" or MSA. From the RFC 2476:
> SMTP was defined as a message *transfer* protocol, that is, a means
> to route (if needed) and deliver finished (complete) messages.
> Message Transfer Agents (MTAs) are not supposed to alter the message
> text, except to add 'Received', 'Return-Path', and other header
> fields as required by [SMTP-MTA].
> However, SMTP is now also widely used as a message *submission*
> protocol, that is, a means for message user agents (MUAs) to
> introduce new messages into the MTA routing network. The process
> which accepts message submissions from MUAs is termed a Message
> Submission Agent (MSA).
> So, yes, in this case, they are definitely distinguishable.
> But, even in the general case, mail clients like thunderbird speak SMTP.
> No one will argue that T-bird is a server, so I fail to see what you're
> at here. SMTP is a client server protocol, which means that there will
> be clients and there will be servers. Servers may then turn around and
> as clients too, but they don't have to.
> Tanner Lovelace
> clubjuggler at gmail dot com
> (fieldless) In fess two roundels in pale, a billet fesswise and an
> increscent, all sable.
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