Windows CE uses a MailAtt structure to hold information about an attachment to a mail message. The members identify the attachment and specify the name and status of the attached file. An attachment is the attached file plus a header. The file name is registered in the szOriginalName member of the MailAtt structure and the header is the MailAtt structure itself.
An attachment can be classified as local or non-local. A local attachment consists of the header and a locally-stored copy of the original file. A non-local attachment has only the header with the name of the attached file. The actual file is not stored on the Windows-based CE device. The file name is simply a placeholder for the attachment. Non-local attachments are possible only when they are attached to a service-linked message.
Multiple attachments to a message are arranged in the MailAttArray structure. Because a file can be attached to a message more than once, it is possible that conflicts arise in the name space of the local files of the attachment. When this happens, Windows CE automatically resolves the name conflicts.