List archives provided by Mailman 3 in mbox format have invalid Date: header value. For example https://lists.fedoraproject.org/archives/list/perl-devel%40lists.fedoraproject.org/export/1.mbox.gz?start=2015-09-01&end=2015-10-01 contains e-mail <!20150903075617.!GD2297@dhcp-0-146.brq.redhat.com> with these headers:

{{{
From ppisar at redhat.com Wed Nov 18 01:54:07 2015
Content-Type: multipart/mixed; boundary="===============1245788734224852802=="
MIME-Version: 1.0
From: Petr Pisar <ppisar at redhat.com>
To: perl-devel at lists.fedoraproject.org
Subject: ExtUtils-MakeMaker-7.06 breaks some builds in F24
Date: 2015-09-03 09:56:17 +0200
Message-ID: 20150903075617.GD2297@dhcp-0-146.brq.redhat.com
}}}

The Date does not conform to RFC 5322, section 3.3 http://tools.ietf.org/html/rfc5322#section-3.3. There should be:

{{{
Date: Thu, 03 Sep 2015 09:56:17 +0200
}}}