mail notification uses wrong subject display when splitted?

Some mail servers seem to have a problem with the base64 encoded subject line in the mail header, in case it is splitted over 2 lines.

As an example:
=?UTF-8?B?VG9waWMgcmVwbHkgbm90aWZpY2F0aW9uIC0gIkF1dG9tYXRpYyByZWNvbmNp?=
=?UTF-8?B?bGlhdGlvbiI=?=

This ends up as:
Subject: =?UTF-8?B?VG9waWMgcmVwbHkgbm90aWZpY2F0aW9uIC0gIkF1dG9tYXRpYyByZWNvbmNp?=
Message-Id: <0M86AX-1NXeof1OhF-00vThA@mx.kundenserver.de>
Date: Thu, 25 Feb 2010 16:23:40 +0100
Envelope-To: thb@net-bembel.de
From: www-data@bluemchen.kde.org
X-Length: 2985
X-UID: 125916

=?UTF-8?B?bGlhdGlvbiI=?=
From: <noreply@forum.kde.org>

As you can see, the mail is messed up with the X-UID.
I don't know enough about mails, but i was told a simple whitespace in the second line of the splitted subject should be enough.

So a possible fix would be to change "$delimiter = "\r\n ";" in the mail_encode() function to "$delimiter = "\r\n\s ";"