Need email server aid

[Chuck Kuecker]

Hello,

I am running Ubuntu 9.10, with postfix and dovecot for my email server. 
I host my own domain.

The Ubuntu machine relays emails from my Windows machine just fine, but 
when I try to relay an email from an embedded system I am working with, 
that resides on my local network, I get error messages in mail.log - 
'relay access denied'. Sending email from the embedded system to my 
local email account works fine.

I have the embedded system 'from' email set to my email address - but it 
seems to make no difference if I use 'device at ckent.org' instead of 
'ckuecker at ckent.org' - I can send to 'ckuecker at ckent.org', but any 
attempt to send out of my local network returns the error.

I've enabled the entire local network here in /etc/postfix/main.cf - 
mynetworks = 127.0.0.0/8, 192.168.0.0/16. My Windows machine SMTP is set 
to use TLS, if available, and my user name. I'm thinking that I need to 
send my user name and password somehow, in order to get relaying to 
work. I don't see any SMTP commands that would do this.

What am I missing here?

Chuck Kuecker