W3C home > Mailing lists > Public > xml-dist-app@w3.org > September 2006

Re: ISSUE: Rewriting of destinations

From: <noah_mendelsohn@us.ibm.com>
Date: Tue, 5 Sep 2006 21:57:59 -0400
To: David Hull <dmh@tibco.com>
Cc: "xml-dist-app@w3.org" <xml-dist-app@w3.org>
Message-ID: <OF5CA92A5F.F4F23B74-ON852571E1.000A41D2-852571E1.000ACD83@lotus.com>

David Hull writes:

> If I send an email To: xml-dist-app@w3.org, the To: field will still be 
> xml-dist-app@w3.org when the message arrives (I just checked :-). 

I've said this two or three times now.  If you try it in my email system, 
with a locally defined mailing list (I.e. one in my local name and address 
book), the destination IS rewritten.  That's because if it weren't 
rewritten, and you tried to Reply All, you'd be trying to send to a 
mailing list that's only known on my local machine.  By contrast, mailing 
lists defined on central servers are not rewritten, though interestingly 
in Lotus notes, our internal mailing lists are expanded at the gateway to 
the internet.  So, if I send:

To: Some-Internal-IBM-Group
cc: dmh@tibco.com

Our internal folks will all see the same unmodified headers as above.  You 
may see in the To: field the exanded list of interent email addresses for 
the members of "Some-Internal-IBM-Group", so that your replies will work 
properly.  I believe I'm oversimpifying the rules actually used here, but 
the spirit is right.

The point is that your email system is an existence proof that at least 
some emails are not rewritten.  Mine is a proof that some are.  That 
disproves your assertion that in general email systems don't do such 
things.

As I've said before, I think that some multicast systems rely on the 
sender to explicitly target each message differently, and indeed sometimes 
to edit each with instructions on which downstream nodes are to be the 
targets of further relays (the message to node 1 says to send on to odd 
numbered nodes, the message to node 2 says to send to even).  In other 
systems, there is no need to rewrite the messages, presumably because the 
underlying transport or some downstream gateway does the rewriting for 
you.

--------------------------------------
Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
--------------------------------------
Received on Wednesday, 6 September 2006 01:58:34 GMT

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