"extended Mapi" Challenge For C++ Gurus

Hi C++ Coders,
Well for those of you who have tried building aplications that have to send automaticaly generated mail using the Mailing API (MAPI) you must have definitely come across the Simple MAPI. A very simole simple API and so much fun to use in C++, VB, and so on. But the API is quite limited in its capability. I recently tried developing a bulk-mailing application and of course having exhausted the features of simple MAPI without being able to generate a suitable solution, I turn to Entended MAPI.
The problem is . . . there hardly seem to be any worth while documentation on Extended MAPI anywhere. Now lest you acuse me of being lazy, I have ran searches on Yahoo and Google for Extended MAPI for days and I only seem to find more people out there with questions than there are answers to using this cryptic API that seems to be shrouded in Mystry. Most mailing programs of note use Extended MAPI so why is the documentation for this API scarce?
Does anyone have any helpful article, book, link or code on this subject?