[Mailman-Developers] [Bug 985149] Add List-Post value to permalink hash input

[Barry Warsaw]

On Apr 20, 2012, at 01:43 PM, Barry Warsaw wrote:

>Note that RFC 5064 defines the Archived-At header.  IMO, this would be the
>appropriate place to add any list-specific namespace discriminator.  Also, RFC
>2369 defines the List-Archive header, which could contain the base URL to the
>archiver, including the List-ID information.

Note that one problem with including the List-ID value in the hash is that if
you receive an off-list copy of the message, you may not be able to calculate
the hash to that message in the archive, because you will not have the List-ID
header in your copy.  You will still have the Message-ID.

It will *usually* be possible to calculate this, given a reasonable assumption
of the mapping from the list posting address (in the To field, remember you
also won't have the List-Post header!).  E.g. if you see:

    To: test at example.com

you can reasonably guess that List-ID will be <test.example.com>.  It may not
be though, or the list may have gotten migrated and given a different List-ID.

That was the beauty of the original algorithm; all you needed was the
Message-ID.

I don't think that's a fatal flaw to not include the List-ID in the hash,
since I think it will be rare in practice for List-ID to be incalculable from
the To header, but it's something to be aware of.

-Barry