On Fri 05/Feb/2021 22:53:34 +0100 Dave Crocker wrote:
On 2/5/2021 1:44 PM, Valdis Klētnieks wrote:
It's a plausible design that the agent doing final delivery accepts
responsibility for delivery to multiple local mailboxes (I've often had things
that ended up delivering to root@localhost and valdis@localhost with one
invocation of the local delivery agent, for example).
Even then, actual delivery usually happens one mailbox at a time, in a loop.
Should the agent generate two Delivered-To: headers, or does it *actually*
get generated appropriately for each copy (at a time later than when the
agent accepted responsibility)?
The second, IMHO. Adding multiple Delivered-To: at once, one for each mailbox,
would violate the MUST NOT in Section 5.
The question for the specification is whether it makes clear what the
specification calls for. I think it does, but if readers aren't clear about
it, it would be good to know what about it isn't clear enough.
Perhaps, the case of delivery to multiple mailboxes should be anticipated in
Section 3.
A different question is how to implement the specification, so as to conform to
the specification.
For storing a separate copy for each recipient, that seems straightforward.
For sharing a single copy of the message among multiple recipients, the answer
probably is not straightforward...
The case of shared IMAP folders is also straightforward. The Delivered-To:
contains the mailbox of that folder if it has one, or the mailbox of the
recipient whose filter directed the message to that folder.
If the mail store implements messages to multiple recipients as files with
multiple links, I see no way it can add a Delivered-To:. Such a complicate
system perhaps might resort to adding it on the fly whenever a MUA downloads
the message. Or it can do without. Or maybe it may make sense to have
something like Delivered-To: user-group-XXXX(_at_)example(_dot_)com.
Best
Ale
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