Network Working Group C. Newman Request for Comments: 3848 Sun Microsystems Category: Standards Track July 2004 ESMTP and LMTP Transmission Types Registration Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2004).
AbstractThis registers seven new mail transmission types (ESMTPA, ESMTPS, ESMTPSA, LMTP, LMTPA, LMTPS, LMTPSA) for use in the "with" clause of a Received header in an Internet message. 2], IANA maintains a registry  of "WITH protocol types" for use in the "with" clause of the Received header in an Internet message. This registry presently includes SMTP , and ESMTP . This specification updates the registry as follows: o The new keyword "ESMTPA" indicates the use of ESMTP when the SMTP AUTH  extension is also used and authentication is successfully achieved. o The new keyword "ESMTPS" indicates the use of ESMTP when STARTTLS  is also successfully negotiated to provide a strong transport encryption layer. o The new keyword "ESMTPSA" indicates the use of ESMTP when both STARTTLS and SMTP AUTH are successfully negotiated (the combination of ESMTPS and ESMTPA). o The new keyword "LMTP" indicates the use of LMTP .
o The new keyword "LMTPA" indicates the use of LMTP when the SMTP AUTH extension is also used and authentication is successfully achieved. o The new keyword "LMTPS" indicates the use of LMTP when STARTTLS is also successfully negotiated to provide a strong transport encryption layer. o The new keyword "LMTPSA" indicates the use of LMTP when both STARTTLS and SMTP AUTH are successfully negotiated (the combination of LSMTPS and LSMTPA). o The references for the ESMTP and SMTP entries in the registry should be updated to the latest specification  since both RFC 821 and RFC 1869  are obsoleted by RFC 2821.
and reduce their ability to correct security abuses after they happen. The result of such misguided efforts is usually a reduction of the overall security of the systems.  Hoffman, P., "SMTP Service Extension for Secure SMTP over Transport Layer Security", RFC 3207, February 2002.  Klensin, J., Ed., "Simple Mail Transfer Protocol", RFC 2821, April 2001.  Myers, J., "SMTP Service Extension for Authentication", RFC 2554, March 1999.  Myers, J., "Local Mail Transfer Protocol", RFC 2033, October 1996.  Klensin, J., Freed, N., Rose, M., Stefferud, E., and D. Crocker, "SMTP Service Extensions", STD 10, RFC 1869, November 1995.  Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC 821, August 1982. http://www.iana.org/assignments/mail-parameters>
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