2.2.10.2.1 PidTagMessageClass Property

Type: PtypString ([MS-OXCDATA] section 2.11.1.2)

The value of the PidTagMessageClass property ([MS-OXCMSG] section 2.2.1.3) MUST be "IPM.OLE.CLASS.{00061055-0000-0000-C000-000000000046}".