Yeah you're on the right track, but you'll also need to make sure postfix knows to allow certain hosts to us it as a relay. You can do this right in the <a href="http://main.cf">main.cf</a> file with something like the following:
<br>mynetworks: <a href="http://192.168.0.0/27">192.168.0.0/27</a>, <a href="http://127.0.0.0/8">127.0.0.0/8</a><br><br>Either that or setup SMTP AUTH and TLS to restrict relaying by user account. There are a number of ways to setup your client machines with postfix/exim/sendmail/ssmtp to be an auth client.
<br><br><br><div class="gmail_quote">On Dec 27, 2007 11:30 AM, Tim Wilson <<a href="mailto:wilson@visi.com">wilson@visi.com</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hey everyone,<br><br>I'd like to create a little server running Ubuntu and postfix that<br>would be a mail relay for a few other servers in our school district.<br>For example, rather than configuring our Moodle and nagios servers to
<br>send their own mail, I'd like to point them at the mail relay and have<br>it send the mail for them. This box would not need to receive mail,<br>only send it. We run GroupWise for our staff email accounts, but it<br>
can be a hassle to configure other servers to send mail through GW<br>sometimes.<br><br>I started putting together a <a href="http://main.cf" target="_blank">main.cf</a> file for postfix and got this far<br>(in addition to the other default settings):
<br><br>mydestination = $myhostname, localhost.$mydomain, $mydomain<br>myhostname = bison<br>mydomain = <a href="http://buffalo.k12.mn.us" target="_blank">buffalo.k12.mn.us</a><br>myorigin = $mydomain<br>relayhost = <a href="http://monitor.buffalo.k12.mn.us" target="_blank">
monitor.buffalo.k12.mn.us</a> # This is our nagios server<br><br>Am I on the right track here?<br><br>-Tim<br><br>--<br>Tim Wilson, The Savvy Technologist<br>Twin Cities, Minnesota, USA<br>Educational technology guy, Linux and OS X fan, Grad. student, Daddy
<br>mailto: <a href="mailto:wilson@visi.com">wilson@visi.com</a> aim: tis270 blog and podcast: <a href="http://technosavvy.org" target="_blank">http://technosavvy.org</a><br><br><br><br>_______________________________________________
<br>TCLUG Mailing List - Minneapolis/St. Paul, Minnesota<br><a href="mailto:tclug-list@mn-linux.org">tclug-list@mn-linux.org</a><br><a href="http://mailman.mn-linux.org/mailman/listinfo/tclug-list" target="_blank">http://mailman.mn-linux.org/mailman/listinfo/tclug-list
</a><br><br></blockquote></div><br><br clear="all"><br>-- <br>Ben Lutgens<br>Linux / Unix Sysadmin