On Tue, Oct 12, 2004 at 08:50:30AM -0700, Steve Atkins wrote: > > Is the "Message-ID" header field a globally unique identifer? > > Not a postgresql related issue, but, yes Message-ID: is, by > definition, a globally unique identifier. If there are two > messages with the same Message-ID then the sender is asserting > that those two messages are identical. See RFC 2822 section 3.6.4.
Except that they usually recommend adding the domain as part of the message-id. This is where your problem comes in. A mail server hiding behind a NAT firewall that's a relay and doesn't receive incoming mail directly, is not going to have a domain. So you'll get things like localhost.localdomain or something completely fake. Indeed, two messages in this thread have this. Secondly, clients creating their own message-ids are not always that great. For example, Outlook, uses the computer name as the domain. They're not likely to be unique worldwide either. You'd still have to be pretty unlucky to get two the same though. It's possible Microsoft mashes the ethernet MAC ID in there too. The answer is, it very very close to unique, but not really guarenteed. All mail systems I'm aware of generate their own ID's anyway, look through the received headers... Hope this helps, -- Martijn van Oosterhout <[EMAIL PROTECTED]> http://svana.org/kleptog/ > Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a > tool for doing 5% of the work and then sitting around waiting for someone > else to do the other 95% so you can sue them.
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