A good email system architecture quickly delivers email with embedded sound, graphics, video files, and HTML forms, while providing for future upgrade and scalability. At a simplistic level, the Messaging Server architecture should:
Accept incoming mail from external sites
Determine the user mailbox to deliver these messages to and route them accordingly
Accept incoming mail from internal hosts
Determine the destination system to deliver these messages to and route them accordingly
Central to an email system architecture is the messaging server itself, a collection of components used to send and deliver messages. In addition to components provided in Messaging Server, the email system also requires an LDAP server and a DNS server. The DNS server must be in place before deploying your email system.
Several factors other than efficiency and scalability influence the Messaging Server architecture. Specifically these are:
See Chapter 11, Developing a Messaging Server Architecture for more information on these topics.