Mail server masquerading problem

Hi,

I'm trying to send mail from a local mailserver in my LAN. My Unix domain is
HADES which is not resolvable on the internet. The mailserver is behind an
OpenBSD firewall.

I'm using the machine (named THANATOS) as my mailserver in Outlook, this
works fine. The problem starts when I try to send mail via a cron job from
the server. (About 10 messages are send each day at 10 pm).

My mail is being returned with this error:

----- The following addresses had permanent fatal errors -----
<(E-Mail Removed)>
(reason: 450 <(E-Mail Removed)>: Sender address rejected: Domain not
found)

In my sendmail.mc file I'm trying to masquerade my local domain by these
adjustments:

MASQUERADE_AS(comsult.nl)dnl
MASQUERADE_DOMAIN(hades)dnl
FEATURE(`allmasquerade')dnl
FEATURE(`masquerade_entire_domain')dnl
FEATURE(`masquerade_envelope')dnl
MAILER(smtp)dnl
MAILER(procmail)dnl

After this I restart the daemon by running these commands in al little
script:

#!/bin/bash
cd /etc/mail
make
m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf # RH Ver 8.0+
newaliases
/etc/init.d/sendmail restart

There are no errors after running this script. I've done every thing I could
think of but it still is not working as it should. Can anyone please help me
out?

Regards,

Joshua

P.S. I'm don't use the newsgroups often so if there is anything missing
please let me know...