MAPI ms-tnef problem

Is it possible to send file attachments using MAPI in not MS TNEF content type e.g. application/octet-stream or so on in Visual C++ ?
As I understand I have to deal with MapiFileTagExt structure and set lpEncoding and lpTag fields, but have no idea how to deal with it.

Problem: TNEF is readable only MS Outlook client (even outlook express or hotmail.com doesn't understand tnef not to mention other mail clients ).


thanks.