I am using Small Business Server 2003 R2 Premium Edition. I recently set-up my network domain and I configured Outlook 2003 & 2007 on the client machines to work with the server. I added all the users under server management and I configured the POP3 settings for each user. The issue I am having is that I can't send out e-mails outside of our networ but I have no problem receiving e-mails from anyone . I could e-mail users just fine but if I try to e-mail anyone else that is not in the domain the e-mail does not go through. I know the issue is somewhere in the server because I had no problems until I installed the server.

FYI: I am using Yahoo as my web host. My Server is in DHCP mode.