Chapter 1. Overview 11
In the intersite communications model represented here, all messages flow through the MTA.
In addition, an MTA (via a connector), and not the Directory Services, performs the intersite
1.3.8 Mail routing in Microsoft Exchange
The MTA in the Microsoft Exchange site is responsible for all message routing. The process
of routing messages within Microsoft Exchange follows these steps:
1. A message is received by the MTA. It can come from a user’s mailbox, a connector, or
2. The MTA evaluates the recipient’s address or addresses to determine if it is within the
same Microsoft Exchange site. If the recipient is in the same site, the message is delivered
to the site Information Store.
3. If the recipient is not found within the same site as the MTA, the MTA matches the
recipient’s address space to an available gateway, connector, or to another MTA.
4. The MTA then sends the message through the selected gateway, connector, or MTA.
5. The message is delivered to the recipient’s system via its own delivery mechanism. For
example, if the recipient has an address denoting another Microsoft Exchange site, the
local MTA routes it to the MTA for the other site and that MTA ensures delivery to its site’s
1.4 Microsoft Outlook
Microsoft Outlook is a messaging client offering from Microsoft. It is designed to operate as
an independent personal information manager, as an Internet mail client using the
POP3/SMTP protocol to send/receive mail or in conjunction with the Microsoft Exchange
server in the backend for group-scheduling, e-mail, and task management. It manages e-mail,
calendars, contacts, tasks, to-do lists, and documents or files on the hard drive. Microsoft
Outlook helps users communicate with others through e-mail, telephone, and group
scheduling. It also allows users to share information via Internet connectivity, Microsoft
Exchange server public folders, and electronic forms as a component of customized
1.5 Lotus iNotes Access for Microsoft Outlook
The Lotus iNotes client offering is not a product but an umbrella brand that encompasses
access to the Domino server with Web browsers, Microsoft Outlook, and POP3 clients. iNotes
represents the extension of Domino messaging and collaboration, personal information
management, and offline services to the users' choice of clients. The iNotes licensing model
also includes access to all Domino services, including messaging and collaborative
Note: If the message is addressed to a distribution list, the list is split into its component
recipients. The routing process is handled independently for each recipient.