a DoS vulnerability associated with conflated Message-IDs?

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+From: Daniel Kahn Gillmor <dkg@fifthhorseman.net>\r
+To: notmuch mailing list <notmuch@notmuchmail.org>\r
+Subject: a DoS vulnerability associated with conflated Message-IDs?\r
+User-Agent: Notmuch/0.11.1 (http://notmuchmail.org) Emacs/23.3.1\r
+       (i486-pc-linux-gnu)\r
+Date: Thu, 08 Mar 2012 11:37:09 -0500\r
+Message-ID: <87k42vrqve.fsf@pip.fifthhorseman.net>\r
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+\r
+--=-=-=\r
+Content-Type: text/plain\r
+\r
+notmuch currently treats all messages with the same Message-ID as\r
+the same message.  I think this could be a vulnerability :(\r
+\r
+If two messages have the same Message-ID, is there a guarantee of which\r
+of these messages will be produced during a notmuch show?\r
+\r
+Either way, it seems to create a potential DoS attack on notmuch users.\r
+\r
+-------\r
+\r
+The attack:\r
+\r
+Let's say there is a public mailing list that Mallory knows\r
+bob@example.org is subscribed to.  alice@example.net sends a message to\r
+the public mailing list detailing some problem that Bob probably needs\r
+to deal with.\r
+\r
+Mallory can just craft a content-free e-mail (or a dozen?) with the same\r
+Message-ID as Alice's message, and send it to bob@example.org.\r
+\r
+If Bob uses notmuch, he is much more likely to read one of Mallory's\r
+bogus e-mails than to read Alice's original message.\r
+\r
+Mallory's e-mail could also be crafted to look like spam, in the hopes\r
+that Bob's spamfiltering scripts would mark the original message's\r
+Message-ID as spam.\r
+\r
+--------\r
+\r
+I don't know how to fix this, and i'd be happy to hear if someone thinks\r
+my analysis above is flawed and this isn't really a problem.\r
+\r
+Any ideas on how to approach this?\r
+\r
+       --dkg\r
+\r
+--=-=-=\r
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+--=-=-=--\r