Uh...
Mail relaying is off by default. I think it has been for a couple of releases now.
The problem is that you're not on your network and you want to send mail, using a machine which *is* on your network.
Now, you can configure the mail server to accept mail from people not on it's network, and to send them out. And this is called a mail relay, because it's relaying mail from some place to another - essentially, taking the baton from the previous mailer.
Problem is this : How do you stop others from also using your mail system from sending *their* mail? How does your machine know it's you, and to only relay mail from you, and not from joe spammer who discovered your machine and is now using it to send out his 15k emails describing the exciting opportunity of working from home...
The answer is smtp.auth :
SMTP AUTH allows relaying for senders who have successfully authenticated themselves. Per default, relaying is allowed for any user who authenticated via a trusted mechanism, i.e., one that is defined via
[blah]
http://www.sendmail.org/~ca/email/auth.html
I would *seriously* advise calling someone in to set this up though. Operating an 'open relay' is exceptionally bad. You won't make friends, and an incorrectly configured gateway can lead to your mail not reaching *anyone* because it's been blacklisted.
Oh.. And the relaying denied is a *good* thing. If your less than honourable employee's had been less honourable, they would have opened it up and let the world in to use your mail server
Slick.
"Relaying Denied" by Sendmail
