Integrating Client Access into Exchange Server 2007 Design

Although the Exchange server is a powerful systems component, it is only half the equation for an email platform. The client systems comprise the other half, and are a necessary ingredient that should be carefully determined in advance.

Outlining Client Access Methods

Great effort has been put into optimizing and streamlining the client access approaches available in Exchange 2007. Not only have traditional approaches such as the Outlook client been enhanced, but support for nontraditional access with POP3 and IMAP clients is also available. The following options exist for client access with Exchange 2007:

. Outlook MAPI—The full Outlook client has been streamlined and enhanced. MAPI communications with Exchange 2007 systems have been compressed, and the addition of slow-link detection enables speedy mail retrieval for remote users. Outlook versions that support access to Exchange 2007 servers are limited to the 2002, 2003, and 2007 versions of Outlook.

. Outlook Web Access (OWA)—The Outlook Web Access (OWA) client is now nearly indistinguishable from the full Outlook client. The one major component missing is offline capability, but nearly every other Outlook functionality is part of OWA.

. ActiveSync—ActiveSync provides for synchronized access to email from a handheld device, such as a Pocket PC or other Windows Mobile device. It allows for real-time send and receive functionality to and from the handheld, through the use of push technology.

. Outlook Anywhere—Outlook Anywhere (previously known as RPC over HTTP) is a method by which a full Outlook client can dynamically send and receive messages directly from an Exchange server over an HTTP or Hypertext Transfer Protocol Secure (HTTPS) web connection. This allows for virtual private network (VPN)-free access to Exchange data, over a secured HTTPS connection.

. Post Office Protocol 3 (POP3)—The Post Office Protocol 3 (POP3) is a legacy protocol that is supported in Exchange 2007. POP3 enables simple retrieval of mail data via applications that use the POP3 protocol. Mail messages, however, cannot be sent with POP3 and must use the SMTP engine in Exchange. By default, POP3 is not turned on and must be explicitly activated.

. Internet Message Access Protocol (IMAP)—Legacy Interactive Mail Access Protocol (IMAP) access to Exchange is also available, which can enable an Exchange server to be accessed via IMAP applications, such as some UNIX mail clients. As with the POP3 protocol, IMAP support must be explicitly turned on.

NOTE

Exchange 2007 supports the option of disallowing MAPI access or allowing only specific Outlook clients MAPI access. This can be configured if an organization desires only OWA access to an Exchange server. It can also, for security reasons, stipulate that only Outlook 2007 and Outlook 2003 can access the Exchange server. The Registry key required for this functionality is the following:

Location:HKLM\System\CurrentControlSet\Services\MSExchangeIS\ParametersSystem Value Name: Disable MAPI Clients

Data Type: REG_SZ

String: Version # (i.e. v4, v5, etc)

See Microsoft TechNet Article 288894 for more information:

http://support.microsoft.com/default.aspx?scid=KB;EN-US;288894

Each organization will have individual needs that determine which client or set of clients will be supported. In general, the full Outlook client offers the richest messaging experience with Exchange 2007, but many of the other access mechanisms, such as Outlook Web Access, are also valid. The important design consideration is identifying what will be supported, and then enabling support for that client or protocol. Any methods that will not be supported should be disabled or left turned off for security reasons.