Subject: I-D Action:draft-vesely-vhlo-06.txt

From: [email-masked]
Date: Wed, 16 Jun 2010 08:00:01 -0700 (PDT)

A New Internet-Draft is available from the on-line Internet-Drafts directories.

	Title           : Verified Hello SMTP extension
	Author(s)       : A. Vesely
	Filename        : draft-vesely-vhlo-06.txt
	Pages           : 26
	Date            : 2010-06-16

Verified Hello (VHLO) is an SMTP extension for managing authorization
by policy, as done for whitelisting messages.  The VHLO command verb
provides for weak authentication of SMTP clients and policy
negotiation.

Policies and reputation are being increasingly used to identify
messages worthiness.  However, they are currently enforced by
rejecting SMTP transactions, or discarding messages.  Feedback is
scarce, also because reply codes are difficult to interpret
automatically.  Negotiation is not provided for.  VHLO is designed so
that servers can provide feedback to their clients about which
vouching services or authentication methods they require.
Credentials can also be negotiated on the fly, in order to allow
clients to learn whether messages will be whitelisted by the
receiving server before actually transmitting them.  Negotiation and
feedback are intended to ease rapid diffusion of popular reputation
systems and authentication methods.  A IANA register is defined for
extending the set of available methods.

The VHLO command is similar to EHLO, but accepts a series of
parameters.  The sender communicates the mail domain name of the
organization on whose behalf it operates, along with any vouching
services (VBR) for its reputation.  On the other hand, the sending
host's affiliation with that mail domain is checked by DNS lookups
(MX, PTR, or SPF) or using DKIM.  DNSBLs and Greylisting are also
considered.

Weakly authenticated clients enjoy an intermediate level of trust:
they have no relying privileges, but may attempt to deliver mail to
local users, are whitelisted from some filters, and may receive DSNs
and feedback-loop abuse reports as needed.  However, failing to
succesfully negotiate VHLO authentication does not preclude a
client's ability to relay mail: It may relay as usual; that is to
say, without knowing whether the credentials it tries to provide have
any meaning for the receiving server.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-vesely-vhlo-06.txt

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

Below is the data which will enable a MIME compliant mail reader
implementation to automatically retrieve the ASCII version of the
Internet-Draft.