Microsoft's Office team had to remove some of the features from Outlook 2013 that are out of date and aren't utilized by a large number of users. This allows them to focus on improving the current Outlook features. A lot of features have been removed from Outlook 2013 including the support of .DOC (Word 97-2003) and .XLS (Excel 97-2003) file formats.Here are the other features that have been removed from Outlook 2013:
Exchange "Classic Offline" Mode
Outlook 2013 no longer support "Classic Offline" Mode for Microsoft Exchange accounts. Users in this configuration will be upgraded to Cached Mode when they install Outlook 2013.
"Deliver to PST" for Exchange accounts
Exchange accounts will no longer be able to have their delivery location be a PST file (rather an .OST). Users in this configuration will be upgraded to Cached Mode (with an .OST file) when they install 2013.
Calendar Publishing to Office.com (PubCal)
Users will no longer be able to publish calendars publicly to Office.com using Outlook 2013, and the Office.com calendar sharing service will be shutting down for older versions of Outlook as well.
VPN and Dialup Settings
VPN and dialup preferences are no longer independently configurable in Outlook. These options were previously located on the Send/Receive tab in Outlook 2010. As a workaround, affected users are encouraged to set these options system wide in the Windows Control Panel.
Outlook search via the Windows Shell
Outlook 2013 will no longer surface search results for mail and calendar items in Windows Explorer or via the start menu. Users can still utilize all of Outlook's search functionality from within the app itself.
Journaling
The Journal as a top-level module no longer exists in Outlook 2013. Journal entries can still be accessed via the Journal folder in the Folder List module. Also, the ability to 'auto-journal' your Outlook actions is gone in 2013.
Import/Export to Legacy Applications
Outlook has traditionally supported importing and exporting data to and from many different file formats. Many of the formats Outlook has supported are outdated and are no longer in mainstream use. Outlook will continue to support comma-separated-value (.csv) files as well as .PST files, but other file formats are no longer supported.
This list includes:
- ACT! Contact manager files
- Word 97-2003 (.doc)
- Excel 97-2003 (.xls)
- Outlook Express archives
Legacy Contact Linking/Activities Tab
The Contact Activities Tab is removed from Outlook 2013. This previously provided a way to "link" contacts with other Outlook items, and have them all roll-up in the Activities Tab. The Outlook Social Connector (introduced in Outlook 2010) replaces much of this functionality in a faster, more user friendly fashion.
Source: Outlook blog