Pipermail cannot recognize Date: field like Date: Wed,3 Apr 2002 14:58:26 +0800 correctly, though it understands Date: Wed, 3 Apr 2002 14:58:26 +0800 perfectly. Remember that RFC2822 says a space(FWS) at the head of "date" is optional, not mandatory:

date-time = [ day-of-week "," ] date FWS time [CFWS] date = day month year day = ([FWS] 1*2DIGIT) / obs-day

You can notice the symptom of this bug when you browse date.html in the pipermail archive and find some messages posted on 3rd Apr are at the tail of the date-sorted list of April.

Precisely speaking, the problem is inherited from $prefix/Mailman/pythonlib/rfc822.py . I've checked on Mailman 2.0.8.

WATANABE Katsuhiro Software Research Associates, Inc.