FS#2887 Empty To: and From: email headers in notify messages, To: header also occurs twice

sample:

1 Received: by xxxxxxxx (Postfix, from userid 33)
2 id 54986200BF; Mon, 25 Nov 2013 11:26:49 +0100 (CET)
3 To:
4 Subject: =?UTF-8?B?WyoqKiogd2lraV0gU2VpdGUgZ2XDpG5kZXJ0OiAqKioqKioK?=
5 X-PHP-Originating-Script: 33:Mailer.class.php
6 X-Mailer: DokuWiki
7 X-Dokuwiki-Title: xxxx wiki
8 X-Dokuwiki-Server: xxxxxxxx
9 List-Id: xxxx wiki <wiki.shackspace.de>
10 Date: Mon, 25 Nov 2013 11:26:49 +0100
11 List-Unsubscribe:
12 <http://xxxxxxxx/wiki/doku.php?id=xxxx&do=subscribe>
13 Message-Id: <xxxx@xxxxxxxx>
14 In-Reply-To: <xxxx@xxxxxxxx>
15 To:
16 Cc:
17 From:
18 MIME-Version: 1.0
19 Content-Type: multipart/alternative;
20 boundary="__________5cba5b9403594f1a264535ff2a6642f0XX"
21 Content-Length: 6325
22 Lines: 98
23
24 ...
25

Lines 3, 15: doubled To: header
Lines 15, 17: empty headers

Empty header lines interfere with spam protection

FS#2887 Empty To: and From: email headers in notify messages, To: header also occurs twice

other