Exchange back-end servers typically use the Microsoft Cluster Service for failover support. Exchange front-end servers typically use load balancing clusters.
HTTP, NNTP, POP3, IMAP4, and SMTP virtual servers are available on an Exchange Server 2003 server. The Default HTTP virtual server is called the Exchange server. POP3 and IMAP4 retrieve but do not send e-mail. SMTP is used to send mail. HTTP virtual servers support WebDAV and OWA.
You can control access by using anonymous authentication, basic authentication, and Integrated Windows Authentication. You can encrypt e-mails, including authentication information, if you obtain, install, and associate a certificate, and you can control client access by IP address, subnet, or domain name.
You can set the level of diagnostic logging by using Exchange System Manager and view the results of this logging by using Event Viewer.