Had a customer contact me recently asking why MAPIOpenFormMgr doesn’t work with the Exchange MAPI download. Actually, it wasn’t working in Exchange 2003 either. I’m not sure exactly when it last worked in Exchange’s implementation of MAPI. We might have to go all the way back to the Exchange Client to find a version of Exchange’s MAPI where it worked.
There was more to this story that I wanted to post. A few years ago, on a whim, I debugged why MAPIOpenFormMgr was broken. I found it was looking for a forms manager DLL that Exchange hadn’t shipped in a long long time. However, there was a mechanism for directing Exchange’s MAPI to use a different forms manager, and one of the DLLs Exchange shipped could act as a forms manager. Since this wasn’t likely supported, and no one was asking about it, I filed it away as an interesting tidbit.
Since I did get asked about it, my plan was to post the reg key that controls which forms manager is used with a warning that since it isn’t supported or tested, it’s quite possible it will break on you. However, when I went to try it out, I found that when you try it out with the Exchange MAPI download, you crash right away. This isn’t surprising considering no one’s run the code in 10+ years.
So there’s no point in posting the key, though someone who was really determined could figure it out pretty quickly, and with a little debugging even figure out which DLL to point at. I guess I’ll leave that as an exercise for the reader. The official answer here is that Exchange’s implementation of MAPI doesn’t include a functioning forms manager, so none of the forms management portions of MAPI, such as MAPIOpenFormMgr or MAPIOpenLocalFormContainer, are available.