1. this is a prototype of MIME message encapsulation. it can handle both single-parted as well as multiple-parted messages.

2. it is implemented with the idea of object-orientedness. the multipart messages handler inherits the single-parted handler.

3. the status of it is still at a very primitive level, some of the details haven't been finished. it is mainly used to show the mechanism
and desing at the behind.

4. example of actual usage can be found in AS2Client.cs.