2.2.3.4.1.3 Attachment Creation and Modification Date

If a Content-Disposition header is present on the attachment MIME part, MIME readers SHOULD<160> use its parameters to set creation and modification dates on the Attachment object. If a parameter is missing or its value is not a valid date, the corresponding property value SHOULD NOT be set; however, a MIME reader MAY<161> use current system time to set the PidTagCreationTime property ([MS-OXCMSG] section 2.2.2.3) and the PidTagLastModificationTime property ([MS-OXCMSG] section 2.2.2.2) when the Content-Disposition header values are missing or invalid. Date and time values MUST be translated to UTC.