BizTalk file mask difference for windows 7 and windows server 2008 r2

Problem
When defining a file mask for a specific extension for a file receive location on BizTalk, there’s a difference in which files will be processed depending on the installed OS.

For example, a file receive location on BizTalk 2010 in Windows 7 with extension *.xls will not only process xls files but also xlsx files. While the exact same file mask defined on a receive location in Windows Server 2008 R2 will only pickup files with extension xls.

Cause
This behaviour is caused by the Windows operating system and can be reproduced without BizTalk in a command prompt.

Create 2 files in a folder location: one with extension txt the other with extension txt1. When you type ‘DIR *.txt’ in the command prompt on Windows 7, 2 files will be found. When doing the same on Windows Server 2008 R2, only 1 file will be found.