[Mailman-Developers] From the creation of a ThreadID

[Barry Warsaw]

On Apr 09, 2012, at 11:18 AM, Stephen J. Turnbull wrote:

>On Mon, Apr 9, 2012 at 7:29 AM, Barry Warsaw <barry at list.org> wrote:
>> We had a very lengthy discussion about the hash a year or so ago, when the
>> current algorithm was agreed upon.  I'm too swamped at the moment to dig up
>> the links, but look for input from Jeff Breidenbach and Jeff Marshall.
>
>I believe it's the thread including this message:
>
>http://mail.python.org/pipermail/email-sig/2012-January/000883.html

Shockingly, it's even older than that.  I just did a quick perusal of the page
in the wiki which defines this.  Revision 18 dated 2008-07-03 is the first one
that contain the current description of the algorithm:

"X-Message-ID-Hash is calculated from the Base 32 encoded SHA 1 hash of the
Message-ID header. As with RFC 2822, the angle bracket delimiters are not
considered part of the Message-ID and MUST NOT contribute to the hash."

http://wiki.list.org/display/DEV/Stable+URLs

So yeah, it was a little more than "a year or so ago" :).

>I don't really see the point of not storing all the IDs, anyway.  A
>million message IDs isn't even going to take up a gigabyte! (I think
>it's reasonable to reject a 1000-byte Message-ID as an attack, don't
>you?)  Anybody who's running an archive that receives unique messages
>in mega-message units presumably has enough resources that they can
>afford the odd gigabyte (heck, even in RAM ;-) even if not all the
>messages are going to be stored in the archive due to expiration
>policies or whatever.

Agreed!  As I mentioned to Richard, it's not necessary that X-Message-ID-Hash
be used as the thread id, in part or in whole.  That's not its original
purpose.

The important thing is that any message in the archiver must be discoverable
given its Message-ID or X-Message-ID-Hash.

-Barry
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