property Attachment.Data as Variant
Gets the data of the attachment.

TypeDescription
Variant A safe array of bytes as VARIANT (VT_ARRAY | VT_UI1) or VT_EMPTY if no data is provided for the attachement., 
The Data property returns the data of the attachment as a safe array of bytes. The Save method saves the attachment's data to a file. The for each statement of VB can be used to enumerate the bytes within the array.

The following VB sample enumerates byte by byte, the data of the attachement:

Dim h As Variant
For Each h In a.Data
    Debug.Print h
Next