ietf-822
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Re: Mailing list addition of resent headers

2001-05-24 10:20:52
At 09.40 -0500 01-05-23, Pete Resnick wrote:
This probably confirms my above suspicion: Adding Received fields is something that is done in the transport system (i.e., a 2821 operation). Yes, when you resend and add Resent-* fields, you then introduce the message back into the transport system and it's going to add Received fields. However, adding Received fields is not part of "the process" of resending.

The sematics of the Resent-* fields are: "I (Resent-From/Resent-Sender) got this message and I am resending it to you (Resent-To). I resent it at such-and-so-time (Resent-Date) and I also sent copies of it some other people (Resent-Cc), even some people I may not be telling you about (Resent-Bcc). An identifier for the resending of this message is blah-blah-blah (Resent-Message-ID). The message itself was sent by X (From) to Y (To) and A, B, & C (Cc/Bcc) at some-time (Date)." If you can't figure out who the "I" and the "you" are, chances are Resent-* fields are not appropriate.

Some mailing lists used the "Received" headers to recognize and
stop loops. If an automatic user agent action could reintroduce
a message without its previous "Received" headers, then this
loop control mechanism would fail. There are other loop control
methods which would still work, such as keeping a history of
the Message-ID of recently expanded messages. Some advanced
mailing list servers also recognize the same message even
if its Message-ID has changed. My guess is that they employ
some kind of intelligent checksum on the content of expanded
messages in a data base.

This might be a reason to say that MUAs should not do any
automatic resends of this kind, and without preserving the
incoming "Received" headers.
--
Jacob Palme <jpalme(_at_)dsv(_dot_)su(_dot_)se> (Stockholm University and KTH)
for more info see URL: http://www.dsv.su.se/jpalme/