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@ -206,8 +206,8 @@ determined by the IETF LAMPS WG.
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Header Fields are added by intermediary nodes).
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* Receiving User Facing Message (RUFM): The message used for rendering
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at the receiving side after the Outer Message Header Section has
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been merged with the Inner Message Header Section.
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at the receiving side. Typically this is the same as the Inner
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Message.
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* Essential Header Fields (EHF): The minimum set of Header Fields an
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Outer Message Header Section SHOULD contain; cf. {{outer-msg-hf}}.
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@ -288,7 +288,7 @@ cf. {{main-use-case}}.
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### Backward Compatibility
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<!-- explain what is not correct -->
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The sending side fully supports Header protection as specified in this
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document, while the receiving side does not support the MIME
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specification {{RFC2045}}, ff. correctly; see
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@ -474,6 +474,8 @@ The Inner Message Body is the same as the Original Message Body.
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The Original Message itself may contain any MIME structure.
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<!--
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Alexey: I think this is just saying "The Original Message itself may contain any MIME structure"
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but in a bad way, because "multipart/mixed" is not the only choice here:
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There may also be an additional MIME layer with media type
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"multipart/mixed" in the Outer Message Body to contain the Inner
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Message (wrapped in a "message/RFC822") along with other MIME part(s).
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@ -489,10 +491,14 @@ Unlike the option described in {{option-smime-spec}}, this option does
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not use a "message/RFC822" wrapper to unambigously delimit the Inner
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Message.
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Note: More specific on Parsers (as there are two aspects here)
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Note: it is for further study, whether or not this option is (fully)
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compliant with the MIME standard, in particuar also {{RFC2046}},
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Section 5.1. (Multipart Media Type).
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<!--
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Maybe remove (as suggested by Alexey)
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-->
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The MIME structure of an Email message looks as follows:
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@ -564,6 +570,9 @@ The Inner Message Body is the same as the Original Message Body.
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The Original Message itself may contain any MIME structure.
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<!--
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Alexey: as above: I don't think this helps.
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Either add an example with a more complicated MIME structure,
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or delete this text.
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There may also be an additional MIME layer with media type
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"multipart/mixed" in the Outer Message Body to contain the Inner
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Message along with other MIME part(s).
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@ -613,8 +622,13 @@ The following Header Fields are defined as the Essential Header Fields:
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* Message-ID
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* Subject
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Some of these Header Fields are needed by the Transport (e.g. to
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determine the destination). Furthermore, not including certain Header
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<!-- if not SMTP, it is not relevant to IETF.
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describe that case in a sidenote
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verify 6409 is a good reference, split to RFC5322 and RFC6409
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-->
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Some of these Header Fields are required by the submission service
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{{RFC6409}} (e.g. From, Date). Furthermore, not including certain Header
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Fields may trigger spam detection to flag the message as spam and/or
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lead to user experience (UX) issues.
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@ -624,14 +638,13 @@ Fields MAY be obfuscated. Further Header Fields MAY be obfuscated,
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though simply not adding those to the Outer Message Header SHOULD be
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prefered over obfuscation. Header Field obfuscation is further
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specified in {{obfuscation-outer-HF}}. Header Fields not obfuscated
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SHOULD contain the same values as in the Original Message.
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should contain the same values as in the Original Message.
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The MIME Header Section part is the collection of MIME Header Fields
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describing the following MIME structure as defined in {{RFC2045}}.
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A MIME Header Section part typically includes the following Header
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Fields:
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* MIME-Version
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* Content-Type
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* Content-Transfer-Encoding
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* Content-Disposition
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@ -686,7 +699,10 @@ MAY be obfucated. Those may be replaced by e.g.
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* To: Obfuscated <anonymous@anonymous.invalid>
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Such implementations need to ensure that the Transport has access to
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<!-- define submission service as typically RFC 6409, but also propriatory implmentation exist
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-->
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Such implementations need to ensure that the submission service has access to
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these Header Fields in clear text and is capable of processing those.
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A use case for obfuscation of all Outer Message Header Fields is
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@ -698,6 +714,11 @@ Note: It is for further study to what extent Header Field obfuscation
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### Receiving User Facing Message Header Fields {#rufm-hf}
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The Receiving User Facing Message SHOULD be a verbatim copy of the
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Inner Message.
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<!-- Alternative
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The Receiving User Facing Message is constructed as follows:
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* The Header Section of the Receiving User Facing Message MUST consist
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@ -709,8 +730,19 @@ The Receiving User Facing Message is constructed as follows:
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as the Inner Message Body.
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\[\[ TODO: Do we need to take special care for HFs, which may appear
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multiple times, e.g. Received HF? \]\]
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multiple times, e.g. Received HF?
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Alexey: None of the header fields that we want protecting are allowed to
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appear multiple times.
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The header fields that can appear multiple times are usually trace header fields:
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Received, Authentication-Results, etc. They are prepended to the outer
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Header Section and can never be protected.
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So I think this is just a long way of saying that no extra text is needed here,
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unless you want the document to explain the above.
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\]\]
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-->
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### Header Field Flow
|
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@ -922,7 +954,8 @@ header field may appear in up to three different variants:
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usually contains the Bcc unchanged from the original message,
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i.e. with all recipient addresses.
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The most privacy preserving is to standardize 2a, as in the other
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The most privacy preserving of the alternatives (2a, 2b, and 2c)
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is to standardize 2a, as in the other
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cases (2b and 2c) information about hidden recipients is revealed via
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keys. In any case the message has to be cloned and adjusted depending
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on the recipient.
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