It can take 48 hours for new GAL entries to appear in a user's OAB. I'd like to see new functionality whereby Exchange would search the GAL if it didn't find an entry in the OAB, then insert the search results into the OAB. You can modify the registry on a client PC to make Outlook include the online GAL in directory lookups. To do so, create a new REG_DWORD value under the HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Cached Mode subkey, name it ANR Include Online GAL, and set the value to 1. This setting forces Outlook to go to the online GAL (on a Global Catalog--GC--server) for any lookup that is ambiguous (i.e., one that has multiple matches). However, this behavior generates RPCs between the client and server to resolve directory lookups. Not only does this increase network demand, it also increases the time addresses take to resolve.
Today's messaging systems must cope with larger attachments as people use more graphics in their communications. Outlook 2003 can detect that you want to send an attachment and proposes options, which Figure 2 shows, that can reduce network load: for example, sharing attachments in a Windows SharePoint Services workspace. If the attachment is a graphics file, Outlook lets you resize it.
Outlook 2003 also includes better on-the-wire compression of Messaging API (MAPI) RPCs, and Microsoft has tweaked buffer packing. All these changes contribute to fewer bytes flowing across the wires and a generally snappier performance as you work with messages.
Microsoft says that Outlook 2003 clients smooth out network demand because they generate a constant trickle of network requests to synchronize mailboxes rather than the sporadic bursts of activity that earlier Outlook versions generated. For example, you expect to see heavy network activity early in the workday as clients connect to pick up and send messages. You still see heavier demand at this time with Outlook 2003, but the demand is more constant than the peaks and valleys that occurred with previous versions.
Of course, every environment is different, so the following theory might not work well for you, but Microsoft touts Cached Exchange mode and smarter networking as a foundation for server consolidation. The basic argument is that in the past, you placed servers close to user communities to let users keep working during network outages. This setup can result in lots of servers, perhaps one per branch office. The combination of Exchange 2003 and Outlook 2003 permits you to consolidate branch office servers into centralized datacenters. Users shouldn't notice the difference because Outlook (rather than local network connections) protects them against outages.
Unicode OSTs and PSTs
In earlier Outlook versions, OST and personal folder store (PST) files are in ANSI format and suffer from some limitations, most notably a 2GB file-size limit. As messages and attachments grow larger, you need to be able to store them in files that can grow larger than this limit.
The Unicode versions of the OST and PST can grow larger than 2GB; however, good reasons exist for not letting these files grow much larger than 5GB. First, the files aren't very efficient when they grow larger than 2GB, and your hard disk will have to work to keep the OST updated as new mail arrives. Second, the hard disk is often relatively slow on laptop computers, which compounds the internal inefficiency. Third, Microsoft didn't design PSTs and OSTs to cope with today's large volume of data (i.e., both number of messages and file sizes), and corruptions can occur if you attempt to extend PSTs and OSTs too much. The Microsoft article "How to configure the size limit for both .pst and .ost files in Outlook 2003" (http://support.microsoft.com/?kbid=832925) provides details about how to configure the size limits of these files.
Unicode files are a step forward, but they solve only one major problem--file-size limits--so don't expect much more from them. Note that you can't upgrade an OST or PST file to Unicode format. You have to recreate the file from scratch if you want to use the new format (although if you create a new Unicode PST, you can drag folders into it from the old PST).
Junk-Mail Processing
Spam is easily the most irritating aspect of email, so the Junk E-mail Filter in Outlook 2003 is one of that program's most welcome additions. (See "Outlook 2003's Junk E-mail Filter," March 2004, InstantDoc ID 41655, for a more detailed look at this feature.) Fighting spam has become a crusade at Microsoft, with Outlook's Junk E-mail Filter complementing the Spam Confidence Level (SCL) extension in both the Exchange 2003 Store and the Exchange Intelligent Mail Filter (IMF--see "Deploying Exchange Intelligent Message Filter," September 2004, InstantDoc ID 43151, for more information about this tool). Microsoft's comprehensive antispam strategy provides a way to prevent spam from entering an organization--the job of the Exchange IMF; provides a mechanism to mark suspicious messages for future treatment--the role of the SCL; and provides client-side protection to achieve maximum filtering--what Outlook's junk-mail processing does. The Exchange Edge Server, due in mid-2005, will provide additional spam-fighting capabilities.
Outlook's Junk E-mail Filter uses Microsoft SmartScreen technology (which the Exchange IMF also uses) to detect and delete spam, but only if you run Outlook in Cached Exchange mode or download messages to a local PST. Otherwise, the network overhead for Outlook to scan messages in the server mailbox would be too great. Outlook therefore downloads messages and attachments before performing any junk-mail filtering.
The Outlook 2003 kit includes a 1MB file called outfiltr.dat, which holds information that helps the Junk E-mail Filter detect spam. The information ranges from simple tests that identify messages that have pornographic content to more complex tests that look for patterns that spammers use. Any detection technique based on a static data file will become less effective over time as spammers invent new ways to avoid detection. For this reason, Microsoft regularly provides updated filter files at http://office.microsoft.com/officeupdate.
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