Inside MAPI Profiles

Messaging API (MAPI) profiles are the primary configuration mechanism for Outlook. Profiles let Outlook know which services are available to the end user and the characteristics of those services. For example, the definition and location of a user's offline folder store (OST) and personal folder store (PST) are stored in the profile. You might need to manipulate the contents of profiles to troubleshoot various problems or, more commonly, when you restructure systems or migrate users to new systems. Although many Microsoft tools (e.g., profgen.exe, newprof.exe) and third-party tools are available, they might not always meet your specific needs. Therefore, you might need to roll your sleeves up and get your hands dirty by manipulating MAPI profiles yourself. Before you do that, you need to understand their structure.

MAPI Profile Structure
A MAPI profile is nothing more than a bunch of registry settings and, as such, can be manipulated using many techniques. In this article, I use regedit to look at the contents of profiles, but before I go any further, I want to issue the following warning: Regedit + human being = time to update résumé. Playing with the registry directly is a dangerous pastime and should be avoided whenever possible. Use documented APIs if available because these will ensure that all relevant parts of the registry are updated. If you do make manual changes, always back up the registry before you start. One technique that I employ is to always export a key before changing it so that I have a .reg file that I can import back in if things don't go as expected. . . .