You can now download the Outlook 2007 MAPI Reference from the Microsoft Download Center at http://www.microsoft.com/downloads/details.aspx?FamilyID=4b1b8b22-3c74-4479-bd0d-7b0ee29e8d59&displaylang=en!
Since my last blog post in January, it seems like the major search engines have made some progress on their crawling. When you search for some commonly used MAPI names today, like PidTagBody and IABContainer::IMAPIContainer, the more popular search engines return them on the first page of their search results. While the search engines are still working their way through the approximately 1500 APIs in the Outlook 2007 MAPI reference, you now have a choice to download this reference, install it on your computer in Compiled HTML (CHM) format, view it at your convenience, and search in this CHM file when you are not connected to the Internet.
The Outlook 2007 MAPI Reference documents about 950 properties in a considerable level of detail. The MAPI reference points you to corresponding Microsoft Exchange Server protocol documents if you need further information on most of these properties. If you often work offline, as in a controlled corporate environment, consider downloading the Exchange protocol documents and have them readily available on your computer as well. You can choose to download individual protocol documents or all of the Exchange protocol documents; currently there are 90+ documents available.