A number of features were removed from Outlook 2013. Some features, like Suggested Contacts, were hated by users, others, like the To-Do Bar and Windows Search, were replaced by a less functional feature (Pinned Peeks) or removed completely.
Over the 15 years and 8 versions of Outlook, we've seen a lot of features come and go. It seems that many of the features we like last 2 versions then are either removed or radically changed and less useful.
Microsoft Outlook 2002 departs from previous versions of Outlook by dropping more than a dozen features, some of them quite significant features. Before you upgrade, you might want to check the list below to make sure that a feature you really need hasn't been cut. Collaboration Features | Mail and Fax Services | Internet Mail
Using and troubleshooting Exchange 2003's Outlook Web Access (OWA). Issues and bugs affecting OWA 2003 and solutions.
Not everyone likes RSS support in Outlook, fortunately you can disable the RSS capability using group policy or a registry tweak. You can also remove the RSS folders from your profile. I'll show you how.
Features that are missing when you install Microsoft Outlook 2007 as a standalone application instead of as part of the Office suite.
Outlook 2003 SP3 is the current version of Outlook 2003. Included in Office 2003 is a new Outlook add-in designed for low-end customer relationship management applications, Business Contact Manager. BCM ships in the Professional and Small Business editions. Also see: Business Contact Manager FAQ Overview of the Business Contact Manager for Outlook 2003 Update Windows