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Re: "for" clause on Received: header field

2007-04-30 15:42:22

At 10:23 +0200 on 04/30/2007, Frank Ellermann wrote about Re: "for" clause on Received: header field:

 > Previous standards (RFC 821, 822) did not allowed several
 addresses, so is these multiple mailboxes on "for" clause
 never implemented?

If it's implemented it's not better than Apparently-To, as
noted in 2821 4.4, but the Apparently-To got a "SHOULD NOT".
Why allow an in essence identical damage in the for-clause ?

While I agree that multiple addresses in the for clause for relay-server created Receive headers is a bad idea (and a privacy issue like the above mentioned Apparently to), this should NOT preclude the creation of a single address for clause if the message gets cloned for final delivery once it gets to the destination domain.

IOW: If a message arrives addressed to a(_at_)example(_dot_)com and b(_at_)example(_dot_)com, then none of the Received headers inserted on its way to should have a for clause. OTOH, the server should be allowed, if it wants, to clone the message (so a separate copy exists for each addressee as if the original relaying server was set to NOT group copies to the same domain into a single Multi Rcpt-To transmission) in which case inserting the single addressee for is a non-issue (ie: is in the same class as if this was the only *(_at_)example(_dot_)com address in a multi-address message). If the message is not-cloned but just delivered to each mailbox with no changes, there should be no for clause in the inserted headers.