Version: 1.13.0 (using 4.3.90 (KDE 4.3.90 (KDE 4.4 RC1)), Kubuntu packages) Compiler: cc OS: Linux (x86_64) release 2.6.31-17-generic I have group messages via By Smart Date Ranges. And see the message at 2 January of 2010 in group, named Unknown: http://img39.imageshack.us/img39/9554/kmailunknown.png But the place of this group is correct, near December and Today.
I can confirm this. The bug is caused by ISO-year handling (first days of january 2010 have iso-dates at 2009-W53. More documentation on this can be found here : http://en.wikipedia.org/wiki/ISO_week_date
*** This bug has been marked as a duplicate of bug 179076 ***