Email processes and protocols/Bibliography
RFC-4409, "Message Submission for Mail", R. Gellens, J. Klensin (2006), http://tools.ietf.org/html/rfc4409.
RFC-5321, "Simple Mail Transfer Protocol", J. Klensin, ed. (2008), http://tools.ietf.org/html/rfc5321.
RFC-5322, "Internet Message Format", P. Resnick, ed. (2008), http://tools.ietf.org/html/rfc5322.
RFC-5598, "Internet Mail Architecture", D. Crocker (2009), http://tools.ietf.org/html/rfc5598.
[PnD07] L. Peterson, B. Davie (2007) "Computer Networks: A Systems Approach" 4th ed. Sect. 9.1.1 "Electronic Mail", ISBN 0-12-370548-7.
[Stevens94] W.R. Stevens (1994) "TCP/IP Illustrated, vol. 1, The Protocols", Chapter 28, "SMTP", ISBN 0-201-63346-9.
[Wikipedia08] Simple Mail Transfer Protocol. More details on SMTP, including history, abuse, and related protocols.