http://www.rfc-editor.org/rfc/rfc2442.txt
RFC 2442: The Batch SMTP Media Type, N. Freed, D. Newman, J. Belissent, M. Hoy1998-11-01T23:00:00-00:00This document defines a MIME content type suitable for tunneling an ESMTP transaction through any MIME-capable transport. This memo provides information for the Internet community