CDO & MAPI Programming with Visual Basic:

Sending OLE Objects

MAPI supports embedding one document inside another, a concept known as OLE in Windows parlance. The document to be embedded in the message must have been previously saved as an OLE docfile (see sidebar). To attach it to a message, specify the parameters to the Attachment collection’s Add method as follows:

1. Set the Type parameter to CdoOle.

2. Set the Source parameter to the full path and filename of the docfile.

3. Set the Position parameter to the character position within the message text at which the receiving mail client should render the object.

4. Set the Name parameter to an empty string, or omit it from the parameter list.

Compound Documents, OLE Structured Storage,and DocFiles

In the early 1990s, Microsoft developed a technology called Object Linking and Embedding (OLE). The goal of this technology was to enable users to create compound documents—documents that could contain other documents, even if the contained and container documents were created by applications that knew nothing of each other. This was all in support of Microsoft’s view that users preferred to think in terms of documents rather than applications.

One problem that had to be overcome was how to save such a compound document to disk without creating a separate file for each embedded document. Microsoft’s solution is OLE Structured Storage. OLE Structured Storage is a specification that treats a file as a filesystem unto itself, conceptually having its own internal folders and files. To avoid ...