A friend of mine requested this; as you might already know that Exchange Server 2013 can be installed on Winwk12R2 and also optimized. But none the less older versions of windows server do support Exchange 2013…and the list follows
Exchange Server Version Compatibility
Version | Windows 2000 Server | Windows Server 2003 | Windows Server 2003 R2 | Windows Server 2008 | Windows Server 2008 R2 | Windows Server 2012 |
Exchange 2000 Server | Yes | No | No | No |
No |
No |
Exchange Server 2003 | Yes | Yes | Yes | No | No | No |
Exchange Server 2007 | No | Yes* | Yes* | Yes* | Yes* | No |
Exchange Server 2010 | No | No | No | Yes* | Yes* | Yes* |
Exchange Server 2013 | No | No | No | No | Yes* | Yes* |
* 64-bit editions only supported |