1.3.4 Message Attachments
An Attachment object is used by a client to associate files, Object Linking and Embedding (OLE) objects, other messages, or binary data with a particular Message object. Because Attachment objects are created, maintained, and accessed only in the context of a message, they are considered subobjects. Operations that affect the location of a Message object also apply to its attachments. Clients retrieve information about attachments in a message via an attachments table, which is a Table object, as described in [MS-OXCTABL].