Re: Current status?

Bill Gunshannon wrote:
In article <g9pl82$lh7$4@xxxxxxxxx>,
helbig@xxxxxxxxxxxxxxxxxxxxxxxx (Phillip Helbig---remove CLOTHES to reply) writes:

In article <t_Wvk.2076$U5.1028@xxxxxxxxxxxxxxx>,
=?ISO-8859-1?Q?Jan-Erik_S=F6derholm?= <jan-erik.soderholm@xxxxxxxxx>
writes:


Log watchers, webcam watchers,
etc, anything which sends notification by email when something
"interesting" happens, using its own built-in mail server;

*Server* ?? I set up my cheap Zyxel DSL modem/router to send
notifications to me, but it not a *server*. It uses whatever mail
server it get's after doing a DSN-MX lookup on the receiver
address, and that should be the official SMTP server of my
ISP, as far as I understand.

Why whould anything just needing to *send* a mail have a
smtp *server* implementation ?

You use "server" to mean "receiving end". A more general use, intended here, is "handles traffic". Thus, incoming server and outgoing server.
You are sending your email TO the proper receiving server (via MX), but it is still coming from your machine, not an "official email server". Technically, there is no problem with your scheme, but in practice, such machines on dial-up, volatile IP addresses are the main source of spam, and are thus blocked by more and more people.

Many STMP servers are neither senders nor receivers, but relays.

Actually, the correct terminology is MUA and MTA.
MUA = Mail User Agent.
MUA's originate and terminate email.

MTA = Mail Transport Agent
MTA'a exchange email across the INTERNET.

Nothing but MTA's should talk between email domains. No MUA shoud be
allowed to acess anything but the local MTA. Thus the reason for blocking
port 25 at your firewall for all internal hosts other than your designated
MTA(s). User machines should never be considered MTA's. MTA's are the
machines with the MX record in tghe DNS system. Violating this simple
network engineering principle is why we have the SPAM probledm that we have.
As for relaying, some MTA's relay. One should be very careful about who
one relays for. You shold relay for your internal machines (all the MUA's)
as that is the purpose of an MTA. You should not relay for external
machines and if you do, that is a real quick way to find yourself on
a blacklist.

Email is really not that hard to manage.

bill


Yup. I think that many of the problems arise because MUAs use the same
protocol (SMTP) and port (25) to send mail to MTAs as MTAs use to relay
mail to each other. On the other hand MTAs talk to MUAs (when delivering
mail) using either of 2 different protocols (that I know of), POP3 on
port 110 and IMAP on port 143. (I don't think anything does POP2 on
port 109 any more.) I think if the mail origination and mail relay
functions and protocols had been kept distinct from the start, everything
would be much cleaner and under better control. For example, the way
you want to authenticate a mail originator is very different from the
way you want to authenticate a mail transport agent.

In their defense, SMTP is a "push" protocol (both for originating and
relaying mail), but POP3 and IMAP are "pull" protocols, so there's a
lot more commonality between an MUA sending to an MTA, and an MTA
forwarding mail to another MTA, than between them and mail delivery.
Also, these protocols originated before SPAM was an issue.


--
John Santos
Evans Griffiths & Hart, Inc.
781-861-0670 ext 539
.

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