[ale] [OT] sendmail & masquerading

[dave brooks]

This probably isnt the mailing list for this, but hey, everyone here
seems to be relatively knowledgeable on a vast plethora of subjects, so
I'll go ahead and ask anyhoo. =]

I have a machine that provides NAT to the rest of the machines on my
network.  A machine that sits behind the gateway has a private IP, but I
would enjoy using sendmail onit to send and receive messages locally as
opposed to having to use my gateway as a pop server.  
(I'm planning on adding an alias on the gateway machine, which has a
real IP address, to forward all mail to user at 192.168.1.2) However,
sendmail wants to send out messages from 192.168.1.2 tagged with a
hostname.domain that doesn't exist (due to the fact that it's on a
private IP address).  This causes everything I send out to be returned
with a Data Format Error.  This is what's returned to me:

--

 ----- Transcript of session follows -----
... while talking to hler.amorphous.org.:
>>> MAIL From:<dbrooks at neurotic.amorphous.org> SIZE=460                                         
<<< 501 <dbrooks at neurotic.amorphous.org>... Sender domain must exist
501 dbrooks at hler.amorphous.org... Data format error

--

Obviously, 'neurotic.amorphous.org' is the troublesome hostname, and due
to the fact it doesnt exist, the message bounces.  How can I make this
appear to come from hler.amorphous.org (which is a real hostname, and
can be nslookup'ed)?

http://www.sendmail.org/faq  mentions something about
MASQUERADE_AS(host.domain), but I don't know how to implement this in my
/etc/sendmail.cf file (if I just stick it in there and SIGHUP sendmail,
it doesnt seem to work and still taggs messages with the non-existant"
host name), or even if this is the correct thing to do.

Can anyone help me out to where I can rectify this problem?  I'm a
sendmail dummy. =]

Regards,
Dave Brooks