I have a Small Business Server 4.5 running Exchange5.5.  
The entire network until recently has been Windows98.  I
recently added an XP Pro machine and tried to setup the
email and ran into problems.  The server is not running
DNS, it has 3 real world DNS servers listed under the DNS
tab in TCP/IP properties.  In the host name box the
servers name is listed (SBS1) and in the domain box it
says "fwcham.org" and that is their domain name for the
web and their email.  However the internal domain name
for the network is FWC.  I hope this is making sense so
far.  When the XP client tries to resolve the server
name/user name for exchange it resolves the server as
SBS1.fwcham.org and the user name resolves properly.  
However, Outlook locks up and crashes because it is
trying to go out to the Internet to retrieve mail.  I
guess my question is, if I change the Domain name in the
DNS tab to FWC instead of FWCHAM.ORG what effect will
that have and do you think that will resolve my issue??  
Or should i leave that box blank???  
I hope this makes sense and thanks in advance.
Rich