OT: Email server configuration(s)

[Billy A. Pumphrey]

This is far off topic, but please give me some feedback to which is the
best way for a few things.  Plus I have a problem.

System Info:
OS - CentOS, the latest of about 6 months ago.  I don't know how to get
the version for it
MailScanner - 4.55.10
Sendmail - 8.13.5
Spamassassin - 3.1.3

1. Ever since I messed with the host name, I get an error when the
someone tries to send messages to root.  In this case I used PINE to
locally send to root at woodenMS2.woodmaclw.local and got this error:
      spam at WoodenMS2.woodmaclaw.local on 9/27/2006 10:15 AM
            A configuration error in the e-mail system caused the
message to bounce between two servers or to be forwarded between two
recipients.  Contact your administrator.
            < WoodenMS2.woodmclaw.local #5.3.5 SMTP; 553 5.3.5 system
config error>

The command hostname returns:WoodenMS2.Woodmaclaw.local

2.  Hostname/Domain/DMZ
Is the best way to setup a mail server to put it in a DMZ and have the
host name and domain name be something like: WoodenMS2.woodmaclaw.com?

3.  How many people use MailScanner to scan/archive outgoing email?  I
use it as a gateway to the exchange server.  It has never occurred to me
to use it for outgoing mail, but for policy sakes it would be nice to
archive the email.  (approved policy)  I have not clue on where to start
for setting this up.  

Comments are appreciated.
Thank you