What is the NNTP?  

Network News Transfer Protocol (NNTP) is an application protocol that is used over TCP/IP networks. NNTP defines a set of client and server commands used to access newsgroups.

Exchange 2000 Server uses NNTP to enable Microsoft Outlook 2000 users to participate in online discussions over the Internet. Exchange also enables users running client applications that support NNTP to access newsgroup public folders on computers running Exchange.

Users can read and post items, such as messages and documents, to NNTP newsgroups that are represented in Exchange as public folders; for example, scientists can exchange research information by posting messages to a newsgroup public folder for their area of interest. Other scientists worldwide can read and respond to items in the newsgroup. Items in newsgroups can be replicated to USENET host computers through news feeds.