[CentOS] Configuring sendmail in a corporate environment

I have a stock CentOS 5 system as far as email (sendmail) is  
concerned that is on our corporate LAN.  I am not trying to set up a  
mail server; I merely want our CentOS systems to be able to send out  
emails.  This works as long as the recipient's domain is our local  
domain.  Any email send to recipients that are not in our local  
domain get stuck in the queue:

# mailq
                 /var/spool/mqueue (2 requests)
-----Q-ID----- --Size-- -----Q-Time----- ------------Sender/ 
Recipient-----------
m61D6wC1029257       16 Tue Jul  1 09:06 <XXXX at XXXX.XXXX.com>
                  (Deferred: Connection timed out with  
mx2.emailsrvr.com.)
                                          <alfred at von-campe.com>

It appears that our firewall is not allowing connection to outside MX  
hosts.  I think I need to configure sendmail to forward emails to our  
local smtp host, but I am not sure how to do that.

Alfred