MAPI Properties

Description: Contains the sum, in bytes, of the sizes of all properties on an attachment.
Property ID: $0E20
Property type: PT_LONG
Area: Message attachment

It is recommended that attachment subobjects expose the PR_ATTACH_SIZE property. The sum contained in PR_ATTACH_SIZE includes the size of the PR_ATTACH_DATA_BIN (PidTagAttachDataBinary) or PR_ATTACH_DATA_OBJ (PidTagAttachDataObject) property. Accordingly, PR_ATTACH_SIZE is usually larger than the contents of the attachment alone.
This property can be used to check the approximate size of the attachment before performing a remote transfer by modem and to display progress indicators when saving the attachment to disk. It is particularly useful with attached OLE objects.