I CAN NOT SEND MAIL to users in the internet from the windows box.
 

Dear GURUS:

The Problem:
I CAN NOT SEND MAIL to users in the internet from the windows box.

Current Configuration:

LAN composed of one Linux machine, one Unix box and one Windows box.

Linux server with the following services:
Squid server (OK)
Samba server (OK)
MAIL server (not so good already ...)(postfix and fetchmail)
Apache server (OK)
Local DNS server (seems to be OK ... more or less)

Unix box with some services:
MySQL server (OK)
http server (OK)
... other stuff (not important)

Windows box, no service of course.
I need that the user can browse web (local and external) and be capable of mail transactions,
both local and external using
Explorer and (...) Outlook (sorry, but I'm not alone in the LAN)

Conectivity and general idea of the installation:

A little weird, I recognize, but this is it:

LAN has a hub
(network: 192.168.10) (and domain is mylab.ani -not exactly an FQDN, but something in the like)
(each machine has only one card and one valid IP number, of course)

To the internet, the Linux machine has a modem. Dial-up manually (for the moment, by cron in the future) The connection is performed against a "free" service. I'm not registered there,
so it isn't my ISP. Instead, that service let me go to where my "ISP" is (a friend who generously gives me DNS for my web page www dot mydomain dot com dot ar
and my mail service which is mail dot mydomain dot com dot ar )

Once there, I can retrieve my mail, which is stored at my Linux, and from there, the idea is to deliver mail in my LAN.
The Linux ppp service stores the DNS of the free service thanks to wvdial (/etc/ppp)
And works fine.(I don't (yet) test dial-in. Hope not to find problems there.)

At the Windows machine I am able (currently) to:
* navigate the internet (Squid OK)
* share directories and files (Samba OK)
* see web pages from both http servers (both Apache OK)
* send mail to a local user (a user in the Linux box)
* receive mail from a local user (from the Linux box and from the Unix box as well)
* receive all the mails arrived at my mail box (from anywhere)
* reply mails originated at machines in the LAN.

At the Linux machine (my local MAIL server and local DNS server, among other services)

I can query the mail server (the "isp" server: mail.myexample.com.ar) so I download all the mail arrived, and from one single file (/var/mail/username) I can pick the mails using outlook, provided
that I issued a "fetchmail -f /etc/somefilerc" (by hand, for the moment)

Of course I can receive all the mail (if I should use the Linux as workstation, which is not the idea).

And of course I can send mail to anywhere from the Linux (this one for instance).

As already stated, the Problem is:
I CAN NOT SEND MAIL to users in the internet from the windows box.

That is, whenever I need to send a mail to somedomain.external I get the (not funny) outlook report:
etc etc the message could not be sent ... ... SMTP, ...
"554 <you@whatever.example>: Recipient address rejected: Relay access denied", ...
(554 comes from Postfix).

Seems (???) to be a relay problem ?
Is it my local DNS ?
Should my DNS reflect in some way the ISP's DNS ?

Should I attach (to you)
main.cf
master.cf
virtual
files under /named (DNS files)
any other ?

Thank you

I don't use postfix, so I can't be extremely specific about it. It would seem that the basic installation of postfix only allows email relaying from the local host (127.0.0.1). Relaying is the term given when a mail server acts as a middle-man when receiving mail. The mail is not addressed to an account on the mail server, meaning the mail server has to send it somewhere else. Check your postfix configuration and search for "relay" or something similar (maybe even 127.0.0.1). Then change it to allow relaying for your local subnet. Again, I don't use postfix, so I can't tell you exact settings or files. Maybe someone else will come along and add that info.

I would advise against using unrestricted relaying. Take the time to learn how to specify your network, or you risk your machine being exploited as an "open relay". Spammers would love you, and users would hate you.

Hey Dark Helmet it's me again !

Ok, I'm working on it ... and I'm gonna tell what's up as soon as it'll be working.
But for now, let me share this feeling of the moment ...
the fact (simple fact) of receiving a response SO SOON !!!
Makes me feel really well.
Means that I'm not alone ...
Listen I'm here in Argentina, away from where the action is...
working alone... for YEARS, whithout having a helping hand EVER.
Now I know I'm not alone any more.
There are people who I can ask for help.
That's not few.
That's A LOT.
Really, I mean, I'm very happy to know that, somewhere, out there, someone can be willing (if not succesfull anynway) willing to give a hand... "I don't know exactly, but lokk here or there..." that's just fine !
OK, Do't wanna waste resources (your time, specially) writing this ... but really Thank YOU.
For the willigness.
For the quickness.

AND OF COURSE:
UNIX FOR EVER !!!!!!!!!!!!!!
YEAHHHHHHH.

You're very, very welcome ;)

I actually had to suffer through this myself, but with qmail. It doesn't allow relaying in its default configuration. So I had a feeling it's the same problem. I'm just glad I could lend a hand (if this solves the problem of course).