tlug: Relaying domains

[Dave Gutteridge <dave@example.com>]

Okay, as any of you who know me will attest, I am pretty damned clueless
about everything, and since this is a sendmail issue, I want to tread
veeerrrryyy carefully.
I'm looking at the web page http://www.sendmail.org/tips/relaying.html, and
what it's telling me is that sendmail has defaulted to rejecting mail I
send through outside sources and whatnot. So if i'm logged in via telnet to
my server, i can send mail (which I've tried and it works), but I can't do
it remotely, using Eudora or Outlook or anything.
To remedy this situation, I should have a file called
/etc/mail/relay-domains where I list the places from which my SMTP server
will accept mail that I want relayed onwards. (Stop me if i sound confused).
Now here's where we hit one of those situations where the manual isn't
representative of my set up. I don't have such a file, nor do I have a
directory called /etc/mail/. 
So, being the intrepid explorer that I am, I made /etc/mail/relay-domains,
and I put my work domain in it (avant.co.jp), so that it will accept me
trying to send mail from here. I figure I should also set something in the
sendmail.cf file so that it knows to look for my /etc/mail/relay-domains
file, but I'm scared to touch the cf file, so i restarted sendmail in the
hopes that it would automatically find it. Of course it didn't.
But then while I was doing this, I realised that I work from a laptop, and
i tend to check my mail from all over the place, and there's no way I can
be sure of where I'm going to want to relay from.
So, reading through the web page some more, i see that i can set the thing
to "promiscuous-relay", which is described in such disparaging terms that
it makes me think i want to handle this better.
So what do I do? How can I get sendmail to not be too picky about where I
want to relay from, without opening my machine up to all the spammers in
the world?

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