220.127.116.11 Sending a RopOpenAttachment ROP Request
When sending a RopOpenAttachmentROP request ([MS-OXCROPS] section 18.104.22.168) to open an attachment, the client MUST use a valid value for the AttachmentID field. For more information about opening an Embedded Message object, see section 22.214.171.124.
The client uses the opened Attachment object in subsequent ROPs. It eventually sends a RopRelease ROP request ([MS-OXCROPS] section 126.96.36.199) on the Attachment object and, after doing so, MUST NOT use the Attachment object for any subsequent ROPs.