I'll start this off with a chronology:
2006/Nov/07: ThunderBird 126.96.36.199 released.
2006/Nov/08: I noticed e-mails from our mailing system were no longer arriving.
2006/Nov/09: Correction: they did arrive, but didn't display. The only reason I even realized this was because I checked ThunderBird the moment the e-mail came in. The mailbox showed there was a new e-mail, but none was displayed. The mailbox file certainly had the e-mail - reason for not being displayed was unclear. Visited #thunderbird on irc.mozilla.org , was pointed to the usual document on disappearing e-mails (sadly, there is such a document - http://kb.mozillazine.org/Disappearing_mail (1)). No help. Compacting folders, one of the suggestions, caused the missing e-mail to actually be deleted from the mailbox file. Scary.
2006/Nov/10: Found out the cause - the "References:" header and "Message-Id:" header have the same value (2). Logged a bug: https://bugzilla.mozilla.org/show_bug.cgi?id=360252
2006/Nov/11: Another user logged the same bug under a different bug number: https://bugzilla.mozilla.org/show_bug.cgi?id=360409
2006/Nov/13: Found out about that bug ticket, and suggested my original bug log be marked as duplicate, even though this new one would be, because this new bug ticket already had more discussion. Funny.
2006/Nov/13: A proposed fix is attached to the bug number.
2006/Nov/22: Release notes ( http://www.mozilla.com/en-US/thunderbird/releases/188.8.131.52.html ) updated to note the bug (3)
2006/Nov/24: 1.8 branch contains a fix.
2006/Dec/20: 184.108.40.206 with fix released. No mention of the bug in the release notes ( http://www.mozilla.com/en-US/thunderbird/releases/220.127.116.11.html )
Now I know from past times I have mentioned this, there's a few common responses:
Q. (2) The e-mails are fucked up. Serves you right?
A. No. Yes, the e-mails are technically incorrect. Does that mean that ThunderBird should suddenly ignore it? Keep in mind that 18.104.22.168 did not have this issue. A change in the ThunderBird code suddenly led to this undesirable behavior. Should mailers be fixed? Of course! Should ThunderBird choke? Hell no.
Q. (2) It's just spammers anyway. Just look at the discussion in that bug.
A. You are doing some selective reading. It's not just spammers whose e-mails have these messed up headers. If only that were true, it would make spam filtering a lot easier. For example, the mailing system used at my workplace had this bug. This is a commercial mailing system used mostly for creating 'tickets' a la support / issue tickets/tracking.
Q. It's a rare occurence - probably nobody is affected.
A. Number of e-mails from that mailing system since 2006/Nov/07: 792 . Rare? I would have lost 792 e-mails. I'm not the only person to have hit this issue ( see the bug report, as well as the two MozillaZine threads linked from the bug ). Moreover, these are just the people who *know* they have to deal with the bug. Given that the e-mails simply don't display, and the user would have to check their mailbox file to make sure the e-mails do actually arrive, there is a very high probability that there is a large group of users out there who are simply not aware of the issue - but in the mean time are missing e-mail, and perhaps even deleting it.
Q. (3) If you read the release notes, you would have known about this.
A. This is true only for those who downloaded 22.214.171.124 anew since 2006/Nov/22 when the release notes were updated. Keep in mind that those who already installed 126.96.36.199 - through automatic updates, for example - on 2006/Nov/07 would not have read these notes. Nor would they have been informed about this problem in any which way(4)
(1) In addition, should the user realize "hey, my e-mail seems to be disappearing", they would be likely to end up at the "disappearing e-mail" document. Which, to this date (2006/Dec/20) makes no mention of this bug as a possible cause. Worse yet, the recommended practice of compacting the folder will actually cause the e-mails to be permanently lost.
(4) What's probably the worst part of it all is that, indeed, the Mozilla Foundation did not see fit to announce this problem in such a manner as one might believe to be warranted when e-mails are not being displayed and in fact may be permanently lost. In addition, Slashdot has rejected at least two story submissions on this item. Could you imagine the same happening if it was Outlook not showing and, by way of the user following procedure, deleting them?
So finally the fix is in, but Mozilla has made no mention of having fixed what is a serious flaw in the previous version. Users will, thanks to this fix, suddenly see e-mail pop up as new that has arrived over the past month and a half, and go "wtf?". Worse yet, some of those users will go "WTF!!!" when they realize that suddenly some e-mail was recovered, but the rest is forever lost thanks to having compacted the folder.
In my opinion, Mozilla have handled this issue extremely poorly by downplaying the severity of this bug, the scope of this bug, the widespreadness of this bug, and by not making mention of this bug in any significant way.
Microsoft tells users not to open Word files they did not expect, or come from a source they don't know. People laugh at Microsoft for this. Personally, I think Microsoft at least had the responsibility to issue that statement. Yes, a fix would be better. However, as it stands now, Mozilla failed to deliver a fix in an appropriate timeframe -and- failed to issue a statement.
I'm one of the users who has been migrating from various Microsoft tools to open source ones - OpenOffice, FireFox and ThunderBird being the pillars of that migration. Unfortunately, one of those pillars is looking extremely weathered and fragile now. Although I may not go back to Outlook, having my faith restored in ThunderBird will take its time -and- an attitude change on the part of the Mozilla Foundation.