Date: Fri, 06 Apr 2001 13:08:42 +1000 From: Greg Black <gjb@gbch.net>
The broken software consists of real mail clients out there that people are still using. Some of that software outputs email with dates in this form:
Date: Thu, 21 Dec 2000 09:34:42 EST
But that software is not necessarily broken; it conforms to the standards, so long as by "EST" the intended time zone is -0500.
I have 217 recent messages in my mail folders with those dates. Many of them are from US sites and so are really -0500, but many of them are from Australian sites and mean either +1000 or +1100 with no way for software that wants to sort them to know about the Australian dates.
That certainly has been a problem in the past, but I think it's declining as people gain more experience with the problem. It would be helpful if someone could survey the incidence rate of this problem in general, and whether it's still a problem in practice. In a quick attempt to do this, I just checked all 4444 of the email messages sent to the tz list between 1986-11-24 and 2001-04-04, which I got from <ftp://elsie.nci.nih.gov/pub/tzarchive.gz>. I found 161 messages sent from an .au domain, the first one dated 1990. None of them had the bug that you describe. All 161 messages used the +0000 notation for time zones. (One message dated 1994 got the offset wrong, and used "-0900" instead of "+0930".) Admittedly the tz list is self-selected, but this still suggests that the problem is relatively rare in practice.