I setup my DNS server (AD-I), exchange server 2003 at home. It looks like this: modem - ISA server/DNS - DC/DNS/IIS/Exchange server. I created host records in ISA server for my website. In my DC, I didn't create any hosts. However, when I try to send email out, it's working ad I can also receive email from others. I really don't get it. I didn't setup any MX records and I check the online tool MX lookup, it also tells me that MX records not found. But email is working.... Can someone please tell me why? Thank you.