On July 13, Microsoft announced that Microsoft Office 2010 reached the Technical Preview engineering milestone. Even though the Office 2010 Technical Preview bits and most of the documentation are available to only participants of the Technical Preview program, we're excited to be able to start blogging about new features and documentation.

The Outlook 2010 MAPI Reference (Technical Preview) is one of the first Office 2010 developer references made available to the general public at this milestone. This release of the Outlook MAPI Reference includes documentation for API elements updated for 64-bit MAPI, and a download for Outlook 2010 MAPI header files. If you plan to have existing 32-bit MAPI applications or new MAPI applications running on a 64-bit operating system with 64-bit Outlook, you will need to build your MAPI applications as 64-bit applications with these header files. Other new content in this release includes fast shutdown support for MAPI clients, 38 new properties, and how to link explicitly to MAPI functions. A summary of new features is in What's New in This Edition.

Apart from Outlook 2010 MAPI, Outlook 2010 offers new features in the object model in the Technical Preview release. Some of the major OM features include the following:

  • A new Conversation object that groups Outlook items that belong to the same "thread" across folders and stores. The Conversation object provides methods to navigate and enumerate items in a conversation hierarchy, and access items in a conversation with a new light-weight SimpleItems collection. You can also programmatically manage the assigning of categories, marking items as read or unread, and cleaning up of a conversation in ways similar to that offered in the Outlook user interface.
  • A new SolutionsModule object that allows Outlook applications to expose a set of one or more folders in the Navigation Pane under the new navigation module, Solutions. There is only one Solutions module that all applications share. When the Solutions module shows folders for only one application, the label can be customized, for example, changed from the default label Solutions to Marketing Project. The Solutions module shows folders from each application in its own grouping. Each application has a corresponding solution root folder in the Solutions module. Subfolders can contain items of different item types. One rule is that a solution root folder and its subfolders must reside on the same store. If the solution root folder is the root folder of a store, then all subfolders of the store root folder are displayed under the solution root folder.
  • A new MobileItem object that represents an SMS or MMS message and supports incorporating mobile messages into Outlook applications. Even though the MobileItem object does not have the full functionality as other Outlook items such as the MailItem object, you can programmatically create a MobileItem object, specify the recipients, subject, and message content, and send the MobileItem object using a specific Outlook Mobile Services account.
  • Extensions to the Account object that supports multiple Exchange accounts.
  • Ability to programmatically customize the Outlook user interface in the following areas:

* Explorer Ribbons
* Inspector Ribbons
* Menus
* Context menus
* Contact Card context menus
* Backstage view
You can customize these areas using Ribbon extensibility, and supply Ribbon XML to the GetCustomUI method of the IRibbonExtensibility interface. Use the Ribbon ID for the feature to determine the XML to pass as a returned value in the GetCustomUI method. Your Ribbon XML typically supplies callbacks that let you respond to a button click, or control visibility or the icon of your Ribbon controls. Use the IRibbonControl.Context object to identify the active window containing the user interface that triggers the callback procedure.

Documentation for the Solutions module and customizing Outlook user interface is currently available to participants of the Technical Preview program. Most developer documentation for Outlook 2010 new features will be available to the public before the launch of Office 2010. I will keep you all posted about further documentation availability.