Datasheet

EXCHANGE SERVER ARCHITECTURE 9
and makes creating dedicated server roles much easier. In a small organization with only one
Exchange server, the same server may be assigned the Mailbox, Hub Transport, and Client
Access server roles.
High-Availability Decisions
High-availability decisions do not need to be made at installation time. Unlike previous
versions of Exchange Server, high availability for Exchange Server 2010 databases can be added
incrementally after the initial deployment of the Mailbox server. There is no clustered mailbox
server installation option.
Table 1.1: Server Roles
Server Role Purpose
Mailbox role Supports mailboxes and public folders.
Client Access role Supports functions such as Outlook, Outlook Web App, Outlook Anywhere
(RPC over HTTP), Windows Mobile ActiveSync, POP3, and IMAP4, and
supports web services such as Autodiscover, the Availability service,
and calendar sharing.
Hub Transport rol e Supports message transport functions such as delivering mail locally
(to other Exchange servers in the organization) or externally (to an SMTP
smart host such as an Exchange Edge Transport server). Using transport
rules, the Hub Transport or Edge Transport roles can also help enforce
messaging policies.
Unified Messaging role Supports delivery of inbound voicemail and Outlook Voice Access features.
Edge Transport role Supports separate antispam and antivirus functions for inbound and
outbound messaging. The Edge Transport server is installed on a
stand-alone machine usually in a perimeter network.
Edge Transport Services
The amount of spam and viruses that some organizations receive is staggering. Even small
organizations are receiving tens o f thousands of pieces of spam, dozens of viruses, and hun-
dreds of thousands of dictionary spamming attacks each week. Some organizations estimate
that more than 90 percent of all inbound email is spam or other unwanted content. Keeping
as much of this unwanted content away from your Exchange servers as possible is important.
A common practice for messaging administrators is to employ additional layers of message
hygiene and security. The first layer is usually some type of appliance or third-party SMTP
software package that is installed in the organization’s perimeter network. The problem with
these third-party utilities is that the administrator has to become an expert on an additional
technology.