PowerPoint: Link within Email -> Check out do not work properly

This KB describes the problem exactly and brings up a solution: http://support.microsoft.com/kb/2661910

But in a few sentences.
There are two ways to solve that problem:

1. add a RegKey to all Clients
   Windows Registry Editor Version 5.00
   [HKEY_CLASSES_ROOT\MIME\Database\Content Type\application/vnd.ms-powerpoint.presentation.12]
   "Extension"=".pptx"
2. Set the Browser File Handling setting within WebApplication settings to permissive instead of strict.

Here's a little more information to "Browser File Handling" (what is it)
http://social.technet.microsoft.com/wiki/contents/articles/8073.sharepoint-2010-and-2013-browser-file-handling-deep-dive.aspx