Hi, I just migrate Exchange 5.5 to 2000 and the users can't send or receive internal emails. The exchange server is not setup to send or receive emails. It is primarily use for storing user mailboxes. Therefore there are no pop or smtp virtual server setup on the Exchange. The user are using Outlook as the email client, they are setup to use Interet Mail send and receive email from our ISP's pop and smtp. There are no problem sending or receiving emails from external email accounts. Why and what cause this problem of not able to send and recieved internal emails? Your help is greatly appreciated