2.2 Message Syntax
A Post object can be created and modified by clients and servers. Except where noted, this section defines constraints under which both clients and servers operate.
Clients operate on a Post object by using the Message and Attachment Protocol, as specified in [MS-OXCMSG]. How a server operates on a Post object is implementation-dependent. The results of any such operations MUST be exposed to clients in a manner that is consistent with the Post Object Protocol.