Whether you're already running Microsoft Exchange Server 2003 or are getting ready to migrate from an earlier version, Exchange 2003 Service Pack 1 (SP1) has plenty of improvements to offer. You can break the service pack's contents down into several categories: bug fixes, updates to existing features, updated UIs, and new functionality.

Bug Fixes
In all complex software products, engineers make hundreds of fixes in response to customer reports. Accordingly, SP1 includes a collection of fixes, from small adjustments to major patches. Microsoft has also updated the API that third-party antivirus products use to scan Secure MIME (S/MIME)­encrypted and Transport Neutral Encapsulation Format (TNEF) messages in an effort to detect suspicious attachments. SP1 also improves the level of error reporting in the Offline Address Book (OAB)­generation process—a welcome step because of the OAB's importance for Microsoft Office Outlook 2003 clients that operate in cached Exchange mode. (This improvement is especially handy when you use Exchange 2003 with Outlook 2003 during server consolidation, which inevitably leads to directory churn and the need for frequent OAB downloads.) If errors occur in the OAB-generation process, an Exchange 2003 SP1 server that generates the OAB signals more detailed and complete information to the event log to help administrators debug the problem.

Feature Updates
SP1 includes new Outlook Web Access (OWA) dictionaries that support Arabic, Danish, Finnish, Hebrew, Norwegian, and Swedish. The service pack also updates the list of cell phones that Outlook Mobile Access (OMA) supports and improves the UI that OWA delivers to those devices. You no longer need to use the ExMerge utility in a Recovery Storage Group mailbox-recovery process because SP1 adds a Recover Mailbox Data option to Exchange System Manager (ESM) as part of the Exchange Task Wizard; that option handles the necessary processes. (Of course, ExMerge remains a valuable tool and is still the best method to extract mailbox data from a database.) SP1 also improves Exchange's journaling feature so that it can handle BCC recipients and so that it expands distribution group (DG) recipients before capturing a message (a worthwhile advance, even though full-fledged document archiving and retrieval products still offer more function than Exchange's built-in journaling).

Changes to UIs
Microsoft follows a self-imposed rule to update product UIs only in service packs (or point releases), to ensure that new UIs are fully tested and documented. SP1's most important UI addition provides configuration options that simplify the setup of Remote Procedure Call (RPC) over HTTP connections with Outlook 2003. (I discuss this topic in greater depth in the main article, "Exchange Server 2003 SP1.")

New Functionality
Exchange 2003 supports hot snapshots, but customers have been slow to introduce them into production because few storage and backup-utility providers have moved to support the feature. SP1 includes support for incremental and differential snapshot backups, which might encourage more administrators to use snapshots—providing they have hardware support, of course.